diff --git a/src/webkit/Browser.ts b/src/webkit/Browser.ts
index 8361a6b0fe6f1..de6777544a71d 100644
--- a/src/webkit/Browser.ts
+++ b/src/webkit/Browser.ts
@@ -17,13 +17,12 @@
 
 import * as childProcess from 'child_process';
 import { EventEmitter } from 'events';
-import { Connection, ConnectionEvents } from './Connection';
+import { Connection } from './Connection';
 import { Events } from '../Events';
 import { RegisteredListener, assert, helper } from '../helper';
 import { Page, Viewport } from './Page';
 import { Target } from './Target';
 import { TaskQueue } from './TaskQueue';
-import { Protocol } from './protocol';
 
 export class Browser extends EventEmitter {
   _defaultViewport: Viewport;
@@ -101,7 +100,7 @@ export class Browser extends EventEmitter {
     return this._createPageInContext(this._defaultContext._id);
   }
 
-  async _createPageInContext(browserContextId?: string ): Promise<Page> {
+  async _createPageInContext(browserContextId?: string): Promise<Page> {
     const {targetId} = await this._connection.send('Browser.createPage', {browserContextId});
     const target = this._targets.get(targetId);
     return await target.page();
@@ -146,11 +145,11 @@ export class Browser extends EventEmitter {
   async _onTargetCreated({targetInfo}) {
     let context = null;
     if (targetInfo.browserContextId) {
-      context = this._contexts.get(targetInfo.browserContextId);
       // FIXME: we don't know about the default context id, so assume that all targets from
       // unknown contexts are created in the 'default' context which can in practice be represented
       // by multiple actual contexts in WebKit. Solving this properly will require adding context
       // lifecycle events.
+      context = this._contexts.get(targetInfo.browserContextId);
       // if (!context)
       //   throw new Error(`Target ${targetId} created in unknown browser context ${browserContextId}.`);
     }
@@ -177,8 +176,7 @@ export class Browser extends EventEmitter {
     target.browserContext().emit(Events.BrowserContext.TargetDestroyed, target);
   }
 
-  async _onProvisionalTargetCommitted({oldTargetId, newTargetId})
-  {
+  async _onProvisionalTargetCommitted({oldTargetId, newTargetId}) {
     const oldTarget = this._targets.get(oldTargetId);
     if (!oldTarget._pagePromise)
       return;
diff --git a/src/webkit/Connection.ts b/src/webkit/Connection.ts
index 5444dfc6342e6..43386a6089a1c 100644
--- a/src/webkit/Connection.ts
+++ b/src/webkit/Connection.ts
@@ -89,7 +89,7 @@ export class Connection extends EventEmitter {
         else
           callback.resolve(object.result);
       } else {
-        assert(this._closed, "Received response for unknown callback: " + object.id);
+        assert(this._closed, 'Received response for unknown callback: ' + object.id);
       }
     } else {
       this.emit(object.method, object.params);
@@ -114,16 +114,16 @@ export class Connection extends EventEmitter {
     } else if (object.method === 'Target.dispatchMessageFromTarget') {
       const session = this._sessions.get(object.params.targetId);
       if (!session)
-        throw new Error("Unknown target: " + object.params.targetId);
+        throw new Error('Unknown target: ' + object.params.targetId);
       session._dispatchMessageFromTarget(object.params.message);
     } else if (object.method === 'Target.didCommitProvisionalTarget') {
       const {oldTargetId, newTargetId} = object.params;
       const newSession = this._sessions.get(newTargetId);
       if (!newSession)
-        throw new Error("Unknown new target: " + newTargetId);
+        throw new Error('Unknown new target: ' + newTargetId);
       const oldSession = this._sessions.get(oldTargetId);
       if (!oldSession)
-        throw new Error("Unknown old target: " + oldTargetId);
+        throw new Error('Unknown old target: ' + oldTargetId);
     }
   }
 
@@ -188,28 +188,28 @@ export class TargetSession extends EventEmitter {
       method,
       params
     };
-    debugWrappedMessage("SEND ► " + JSON.stringify(messageObj, null, 2));
+    debugWrappedMessage('SEND ► ' + JSON.stringify(messageObj, null, 2));
     this._out.push(messageObj);
     // Serialize message before adding callback in case JSON throws.
     const message = JSON.stringify(messageObj);
     const result = new Promise<Protocol.CommandReturnValues[T]>((resolve, reject) => {
       this._callbacks.set(innerId, {resolve, reject, error: new Error(), method});
     });
-    this._connection.send("Target.sendMessageToTarget", {
+    this._connection.send('Target.sendMessageToTarget', {
       message: message, targetId: this._sessionId
     }).catch(e => {
       // There is a possible race of the connection closure. We may have received
       // targetDestroyed notification before response for the command, in that
       // case it's safe to swallow the exception.g
       const callback = this._callbacks.get(innerId);
-      assert(!callback, "Callback was not rejected when target was destroyed.");
+      assert(!callback, 'Callback was not rejected when target was destroyed.');
     });
     return result;
   }
 
   _dispatchMessageFromTarget(message: string) {
     const object = JSON.parse(message);
-    debugWrappedMessage("◀ RECV " + JSON.stringify(object, null, 2));
+    debugWrappedMessage('◀ RECV ' + JSON.stringify(object, null, 2));
     this._in.push(object);
     if (object.id && this._callbacks.has(object.id)) {
       const callback = this._callbacks.get(object.id);
@@ -219,8 +219,6 @@ export class TargetSession extends EventEmitter {
       else
         callback.resolve(object.result);
     } else {
-      if (object.id)
-        console.log(JSON.stringify(object, null, 2));
       assert(!object.id);
       // console.log(`[${this._sessionId}] ${object.method}`);
       this.emit(object.method, object.params);
diff --git a/src/webkit/ExecutionContext.ts b/src/webkit/ExecutionContext.ts
index 7c68af0005650..8662be618b547 100644
--- a/src/webkit/ExecutionContext.ts
+++ b/src/webkit/ExecutionContext.ts
@@ -103,7 +103,7 @@ export class ExecutionContext {
                 return void 0;
               throw e;
             }
-          }
+          };
           return this._session.send('Runtime.callFunctionOn', {
             // Serialize object using standard JSON implementation to correctly pass 'undefined'.
             functionDeclaration: serializeFunction + '\n' + suffix + '\n',
@@ -121,7 +121,8 @@ export class ExecutionContext {
           });
         }
         return valueFromRemoteObject(response.result);
-      }).catch(rewriteError);    }
+      }).catch(rewriteError);
+    }
 
     if (typeof pageFunction !== 'function')
       throw new Error(`Expected to get |string| or |function| as the first argument, but got "${pageFunction}" instead.`);
@@ -147,10 +148,10 @@ export class ExecutionContext {
     let serializableArgs;
     if (args.some(isUnserializable)) {
       serializableArgs = [];
-      let paramStrings = [];
-      for (let arg of args) {
+      const paramStrings = [];
+      for (const arg of args) {
         if (isUnserializable(arg)) {
-          paramStrings.push(unserializableToString(arg))
+          paramStrings.push(unserializableToString(arg));
         } else {
           paramStrings.push('arguments[' + serializableArgs.length + ']');
           serializableArgs.push(arg);
@@ -172,7 +173,7 @@ export class ExecutionContext {
         returnByValue: false,
         emulateUserGesture: true
       });
-    } catch(err) {
+    } catch (err) {
       if (err instanceof TypeError && err.message.startsWith('Converting circular structure to JSON'))
         err.message += ' Are you passing a nested JSHandle?';
       throw err;
@@ -198,7 +199,7 @@ export class ExecutionContext {
       if (response.wasThrown)
         throw new Error('Evaluation failed: ' + response.result.description);
       if (!returnByValue)
-        return createJSHandle(this, response.result);;
+        return createJSHandle(this, response.result);
       if (response.result.objectId) {
         const serializeFunction = function() {
           try {
@@ -208,7 +209,7 @@ export class ExecutionContext {
               return void 0;
             throw e;
           }
-        }
+        };
         return this._session.send('Runtime.callFunctionOn', {
           // Serialize object using standard JSON implementation to correctly pass 'undefined'.
           functionDeclaration: serializeFunction + '\n' + suffix + '\n',
@@ -294,7 +295,7 @@ export class ExecutionContext {
 
   async _contextGlobalObjectId() {
     if (!this._globalObjectId) {
-      const globalObject = await this._session.send('Runtime.evaluate', { expression: "this", contextId: this._contextId });
+      const globalObject = await this._session.send('Runtime.evaluate', { expression: 'this', contextId: this._contextId });
       this._globalObjectId = globalObject.result.objectId;
     }
     return this._globalObjectId;
diff --git a/src/webkit/FrameManager.ts b/src/webkit/FrameManager.ts
index f57c82ef0d143..8f6709f1eef0f 100644
--- a/src/webkit/FrameManager.ts
+++ b/src/webkit/FrameManager.ts
@@ -16,17 +16,18 @@
  */
 import * as EventEmitter from 'events';
 import * as fs from 'fs';
-import {helper, assert, debugError, RegisteredListener} from '../helper';
-import {TimeoutError} from '../Errors';
-import {Events} from '../Events';
-import {ExecutionContext, EVALUATION_SCRIPT_URL} from './ExecutionContext';
-import {NetworkManager, Response, Request, NetworkManagerEvents} from './NetworkManager';
+import { TimeoutError } from '../Errors';
+import { Events } from '../Events';
+import { assert, debugError, helper, RegisteredListener } from '../helper';
+import { TimeoutSettings } from '../TimeoutSettings';
 import { TargetSession } from './Connection';
+import { ExecutionContext } from './ExecutionContext';
+import { ElementHandle, JSHandle } from './JSHandle';
+import { NetworkManager, NetworkManagerEvents, Request, Response } from './NetworkManager';
 import { Page } from './Page';
-import { TimeoutSettings } from '../TimeoutSettings';
-import { JSHandle, ElementHandle } from './JSHandle';
 import { Protocol } from './protocol';
 const readFileAsync = helper.promisify(fs.readFile);
+
 export const FrameManagerEvents = {
   FrameNavigatedWithinDocument: Symbol('FrameNavigatedWithinDocument'),
   TargetSwappedOnNavigation: Symbol('TargetSwappedOnNavigation'),
@@ -34,7 +35,8 @@ export const FrameManagerEvents = {
   FrameAttached: Symbol('FrameAttached'),
   FrameDetached: Symbol('FrameDetached'),
   FrameNavigated: Symbol('FrameNavigated'),
-}
+};
+
 export class FrameManager extends EventEmitter {
   _session: TargetSession;
   _page: Page;
@@ -71,8 +73,7 @@ export class FrameManager extends EventEmitter {
     ]);
   }
 
-  _addSessionListeners()
-  {
+  _addSessionListeners() {
     this._sessionListeners = [
       helper.addEventListener(this._session, 'Page.frameNavigated', event => this._onFrameNavigated(event.frame)),
       helper.addEventListener(this._session, 'Page.navigatedWithinDocument', event => this._onFrameNavigatedWithinDocument(event.frameId, event.url)),
@@ -82,8 +83,7 @@ export class FrameManager extends EventEmitter {
     ];
   }
 
-  async _swapTargetOnNavigation(newSession)
-  {
+  async _swapTargetOnNavigation(newSession) {
     helper.removeEventListeners(this._sessionListeners);
     this.disconnectFromTarget();
     this._session = newSession;
@@ -95,7 +95,7 @@ export class FrameManager extends EventEmitter {
 
   disconnectFromTarget() {
     for (const frame of this.frames())
-       frame._setContext(null);
+      frame._setContext(null);
     // this._mainFrame = null;
   }
 
@@ -210,7 +210,7 @@ export class FrameManager extends EventEmitter {
       return;
     /** @type {!ExecutionContext} */
     const context: ExecutionContext = new ExecutionContext(this._session, contextPayload, frame);
-    frame._setContext(context)
+    frame._setContext(context);
     this._contextIdToContext.set(contextPayload.id, context);
   }
 
@@ -282,7 +282,7 @@ export class Frame {
   }
 
   async waitForNavigation(): Promise<Response | null> {
-    //FIXME: this method only works for main frames.
+    // FIXME: this method only works for main frames.
     const watchDog = new NextNavigationWatchdog(this, 10000);
     return watchDog.waitForNavigation();
   }
@@ -521,7 +521,7 @@ export class Frame {
     return this._detached;
   }
 
-  async click(selector: string, options: { delay?: number; button?: "left" | "right" | "middle"; clickCount?: number; } | undefined) {
+  async click(selector: string, options: { delay?: number; button?: 'left' | 'right' | 'middle'; clickCount?: number; } | undefined) {
     const handle = await this.$(selector);
     assert(handle, 'No node found for selector: ' + selector);
     await handle.click(options);
@@ -586,7 +586,7 @@ export class Frame {
       return this.waitForFunction(selectorOrFunctionOrTimeout, options, ...args);
     return Promise.reject(new Error('Unsupported target type: ' + (typeof selectorOrFunctionOrTimeout)));
   }
- 
+
   async title(): Promise<string> {
     return this.evaluate(() => document.title);
   }
@@ -696,7 +696,7 @@ class NextNavigationWatchdog {
   constructor(frame, timeout) {
     this._frame = frame;
     this._newDocumentNavigationPromise = new Promise(fulfill => {
-      this._newDocumentNavigationCallback = fulfill
+      this._newDocumentNavigationCallback = fulfill;
     });
     this._sameDocumentNavigationPromise = new Promise(fulfill => {
       this._sameDocumentNavigationCallback = fulfill;
@@ -742,7 +742,7 @@ class NextNavigationWatchdog {
           break;
       }
     } catch (e) {
-      console.log("_onTargetReconnected " + e);
+      debugError('_onTargetReconnected ' + e);
     }
   }
 
diff --git a/src/webkit/Input.ts b/src/webkit/Input.ts
index f5ae030a09396..19535bd8a92b0 100644
--- a/src/webkit/Input.ts
+++ b/src/webkit/Input.ts
@@ -68,7 +68,6 @@ export class Keyboard {
     const ControlKey  = 1 << 1;
     const AltKey      = 1 << 2;
     const MetaKey     = 1 << 3;
-    const CapsLockKey = 1 << 4;
     if (key === 'Alt')
       return AltKey;
     if (key === 'Control')
diff --git a/src/webkit/JSHandle.ts b/src/webkit/JSHandle.ts
index 7b3c5e8cdf2ac..0caf02a86ae23 100644
--- a/src/webkit/JSHandle.ts
+++ b/src/webkit/JSHandle.ts
@@ -14,16 +14,15 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-import * as path from 'path';
 import * as fs from 'fs';
+import { assert, debugError, helper } from '../helper';
 import { TargetSession } from './Connection';
 import { ExecutionContext } from './ExecutionContext';
-import { Frame, FrameManager } from './FrameManager';
-import { assert, debugError, helper } from '../helper';
-import { valueFromRemoteObject, releaseObject } from './protocolHelper';
+import { FrameManager } from './FrameManager';
+import { Button } from './Input';
 import { Page } from './Page';
-import { Modifier, Button } from './Input';
 import { Protocol } from './protocol';
+import { releaseObject, valueFromRemoteObject } from './protocolHelper';
 const writeFileAsync = helper.promisify(fs.writeFile);
 
 export type ClickOptions = {
@@ -173,7 +172,7 @@ export class ElementHandle extends JSHandle {
       this._client.send('DOM.getContentQuads', {
         objectId: this._remoteObject.objectId
       }).catch(debugError),
-      this._page.evaluate(() => { return { clientWidth: innerWidth, clientHeight: innerHeight} }),
+      this._page.evaluate(() => ({ clientWidth: innerWidth, clientHeight: innerHeight })),
     ]);
     if (!result || !result.quads.length)
       throw new Error('Node is either not visible or not an HTMLElement');
diff --git a/src/webkit/Launcher.ts b/src/webkit/Launcher.ts
index 5f96e0fb57c72..20ff9b5cfd027 100644
--- a/src/webkit/Launcher.ts
+++ b/src/webkit/Launcher.ts
@@ -15,14 +15,12 @@
  * limitations under the License.
  */
 import * as childProcess from 'child_process';
-import * as path from 'path';
+import { debugError, helper } from '../helper';
 import { Browser } from './Browser';
 import { BrowserFetcher } from './BrowserFetcher';
 import { Connection } from './Connection';
-import { debugError, helper } from '../helper';
 import { Viewport } from './Page';
 import { PipeTransport } from './PipeTransport';
-import * as os from 'os';
 
 
 export class Launcher {
@@ -43,7 +41,6 @@ export class Launcher {
       handleSIGINT = true,
       handleSIGTERM = true,
       handleSIGHUP = true,
-      headless = true,
       defaultViewport = {width: 800, height: 600},
       slowMo = 0
     } = options;
@@ -56,7 +53,7 @@ export class Launcher {
         throw new Error(missingText);
       webkitExecutable = executablePath;
     }
-    
+
     let stdio: ('ignore' | 'pipe')[] = ['pipe', 'pipe', 'pipe'];
     if (dumpio)
       stdio = ['ignore', 'pipe', 'pipe', 'pipe', 'pipe'];
@@ -100,8 +97,7 @@ export class Launcher {
     try {
       const transport = new PipeTransport(webkitProcess.stdio[3] as NodeJS.WritableStream, webkitProcess.stdio[4] as NodeJS.ReadableStream);
       connection = new Connection('', transport, slowMo);
-      const browser = new Browser(connection, defaultViewport, webkitProcess
-        , gracefullyCloseWebkit);
+      const browser = new Browser(connection, defaultViewport, webkitProcess, gracefullyCloseWebkit);
       return browser;
     } catch (e) {
       killWebKit();
diff --git a/src/webkit/NetworkManager.ts b/src/webkit/NetworkManager.ts
index ad42a793b66cc..561846e28f87f 100644
--- a/src/webkit/NetworkManager.ts
+++ b/src/webkit/NetworkManager.ts
@@ -310,79 +310,3 @@ export class Response {
     return this._request.frame();
   }
 }
-
-function headersArray(headers: { [s: string]: string; }): { name: string; value: string; }[] {
-  const result = [];
-  for (const name in headers) {
-    if (headers[name] !== undefined)
-      result.push({name, value: headers[name] + ''});
-  }
-  return result;
-}
-
-// List taken from https://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml with extra 306 and 418 codes.
-const STATUS_TEXTS = {
-  '100': 'Continue',
-  '101': 'Switching Protocols',
-  '102': 'Processing',
-  '103': 'Early Hints',
-  '200': 'OK',
-  '201': 'Created',
-  '202': 'Accepted',
-  '203': 'Non-Authoritative Information',
-  '204': 'No Content',
-  '205': 'Reset Content',
-  '206': 'Partial Content',
-  '207': 'Multi-Status',
-  '208': 'Already Reported',
-  '226': 'IM Used',
-  '300': 'Multiple Choices',
-  '301': 'Moved Permanently',
-  '302': 'Found',
-  '303': 'See Other',
-  '304': 'Not Modified',
-  '305': 'Use Proxy',
-  '306': 'Switch Proxy',
-  '307': 'Temporary Redirect',
-  '308': 'Permanent Redirect',
-  '400': 'Bad Request',
-  '401': 'Unauthorized',
-  '402': 'Payment Required',
-  '403': 'Forbidden',
-  '404': 'Not Found',
-  '405': 'Method Not Allowed',
-  '406': 'Not Acceptable',
-  '407': 'Proxy Authentication Required',
-  '408': 'Request Timeout',
-  '409': 'Conflict',
-  '410': 'Gone',
-  '411': 'Length Required',
-  '412': 'Precondition Failed',
-  '413': 'Payload Too Large',
-  '414': 'URI Too Long',
-  '415': 'Unsupported Media Type',
-  '416': 'Range Not Satisfiable',
-  '417': 'Expectation Failed',
-  '418': 'I\'m a teapot',
-  '421': 'Misdirected Request',
-  '422': 'Unprocessable Entity',
-  '423': 'Locked',
-  '424': 'Failed Dependency',
-  '425': 'Too Early',
-  '426': 'Upgrade Required',
-  '428': 'Precondition Required',
-  '429': 'Too Many Requests',
-  '431': 'Request Header Fields Too Large',
-  '451': 'Unavailable For Legal Reasons',
-  '500': 'Internal Server Error',
-  '501': 'Not Implemented',
-  '502': 'Bad Gateway',
-  '503': 'Service Unavailable',
-  '504': 'Gateway Timeout',
-  '505': 'HTTP Version Not Supported',
-  '506': 'Variant Also Negotiates',
-  '507': 'Insufficient Storage',
-  '508': 'Loop Detected',
-  '510': 'Not Extended',
-  '511': 'Network Authentication Required',
-};
diff --git a/src/webkit/Page.ts b/src/webkit/Page.ts
index 80a0f48d7fccc..002d3c5839e69 100644
--- a/src/webkit/Page.ts
+++ b/src/webkit/Page.ts
@@ -21,7 +21,7 @@ import * as mime from 'mime';
 import { TargetSession, TargetSessionEvents } from './Connection';
 import { Events } from '../Events';
 import { Frame, FrameManager, FrameManagerEvents } from './FrameManager';
-import { assert, helper, RegisteredListener } from '../helper';
+import { assert, debugError, helper, RegisteredListener } from '../helper';
 import { valueFromRemoteObject } from './protocolHelper';
 import { Keyboard, Mouse } from './Input';
 import { createJSHandle, ElementHandle, JSHandle, ClickOptions } from './JSHandle';
@@ -70,7 +70,7 @@ export class Page extends EventEmitter {
     this._frameManager = new FrameManager(session, this, this._timeoutSettings);
 
     this._screenshotTaskQueue = screenshotTaskQueue;
-    
+
     this._setSession(session);
     this._setTarget(target);
 
@@ -113,14 +113,11 @@ export class Page extends EventEmitter {
     });
   }
 
-  async _swapTargetOnNavigation(newSession : TargetSession, newTarget : Target)
-  {
-    this._setSession(newSession); 
+  async _swapTargetOnNavigation(newSession : TargetSession, newTarget : Target) {
+    this._setSession(newSession);
     this._setTarget(newTarget);
-
     await this._frameManager._swapTargetOnNavigation(newSession);
-
-    await this._initialize().catch(e => console.log('failed to enable agents after swap: ' + e));
+    await this._initialize().catch(e => debugError('failed to enable agents after swap: ' + e));
   }
 
   target(): Target {
@@ -140,7 +137,7 @@ export class Page extends EventEmitter {
   }
 
   async _onConsoleMessage(event : Protocol.Console.messageAddedPayload) {
-    const {type, level, text, parameters, url, line:lineNumber, column:columnNumber} = event.message;
+    const { type, level, text, parameters, url, line: lineNumber, column: columnNumber } = event.message;
     let derivedType: string = type;
     if (type === 'log')
       derivedType = level;
@@ -148,7 +145,7 @@ export class Page extends EventEmitter {
       derivedType = 'timeEnd';
     const mainFrameContext = await this.mainFrame().executionContext();
     const handles = (parameters || []).map(p => {
-      let context = null;;
+      let context = null;
       if (p.objectId) {
         const objectId = JSON.parse(p.objectId);
         context = this._frameManager._contextIdToContext.get(objectId.injectedScriptId);
@@ -169,7 +166,7 @@ export class Page extends EventEmitter {
     const formattedText = textTokens.length ? textTokens.join(' ') : text;
     this.emit(Events.Page.Console, new ConsoleMessage(derivedType, formattedText, handles, location));
   }
-  
+
   mainFrame(): Frame {
     return this._frameManager.mainFrame();
   }
@@ -239,7 +236,7 @@ export class Page extends EventEmitter {
       };
       if (!cookie.url && pageURL.startsWith('http'))
         item.url = pageURL;
-      await this._session.send('Page.deleteCookie', item).catch(e => console.log("deleting " + JSON.stringify(item) + " => " +e));
+      await this._session.send('Page.deleteCookie', item).catch(e => debugError('deleting ' + JSON.stringify(item) + ' => ' + e));
     }
   }
 
@@ -388,22 +385,22 @@ export class Page extends EventEmitter {
   async _screenshotTask(options?: ScreenshotOptions): Promise<Buffer | string> {
     const params: Protocol.Page.snapshotRectParameters = { x: 0, y: 0, width: 800, height: 600, coordinateSystem: 'Page' };
     if (options.fullPage) {
-      const pageSize = await this.evaluate(() => {
-        return {
+      const pageSize = await this.evaluate(() =>
+        ({
           width: document.body.scrollWidth,
           height: document.body.scrollHeight
-        };
-      });
+        }));
       Object.assign(params, pageSize);
-    } else if (options.clip)
+    } else if (options.clip) {
       Object.assign(params, options.clip);
-    else if (this._viewport)
+    } else if (this._viewport) {
       Object.assign(params, this._viewport);
+    }
     const [, result] = await Promise.all([
       this._session._connection.send('Target.activate', { targetId: this._target._targetId }),
       this._session.send('Page.snapshotRect', params),
     ]).catch(e => {
-      console.log('Failed to take screenshot: ' + e);
+      debugError('Failed to take screenshot: ' + e);
       throw e;
     });
     const prefix = 'data:image/png;base64,';
@@ -421,7 +418,7 @@ export class Page extends EventEmitter {
     this.browser()._connection.send('Target.close', {
       targetId: this._target._targetId
     }).catch(e => {
-      console.log(e);
+      debugError(e);
     });
     await this._target._isClosedPromise;
   }
@@ -516,76 +513,6 @@ type ScreenshotOptions = {
   encoding?: string,
 }
 
-type MediaFeature = {
-  name: string,
-  value: string
-}
-
-const supportedMetrics: Set<string> = new Set([
-  'Timestamp',
-  'Documents',
-  'Frames',
-  'JSEventListeners',
-  'Nodes',
-  'LayoutCount',
-  'RecalcStyleCount',
-  'LayoutDuration',
-  'RecalcStyleDuration',
-  'ScriptDuration',
-  'TaskDuration',
-  'JSHeapUsedSize',
-  'JSHeapTotalSize',
-]);
-
-const PagePaperFormats = {
-  letter: {width: 8.5, height: 11},
-  legal: {width: 8.5, height: 14},
-  tabloid: {width: 11, height: 17},
-  ledger: {width: 17, height: 11},
-  a0: {width: 33.1, height: 46.8 },
-  a1: {width: 23.4, height: 33.1 },
-  a2: {width: 16.54, height: 23.4 },
-  a3: {width: 11.7, height: 16.54 },
-  a4: {width: 8.27, height: 11.7 },
-  a5: {width: 5.83, height: 8.27 },
-  a6: {width: 4.13, height: 5.83 },
-};
-
-const unitToPixels = {
-  'px': 1,
-  'in': 96,
-  'cm': 37.8,
-  'mm': 3.78
-};
-
-function convertPrintParameterToInches(parameter: (string | number | undefined)): (number | undefined) {
-  if (typeof parameter === 'undefined')
-    return undefined;
-  let pixels: number;
-  if (helper.isNumber(parameter)) {
-    // Treat numbers as pixel values to be aligned with phantom's paperSize.
-    pixels = parameter as number;
-  } else if (helper.isString(parameter)) {
-    const text: string = parameter as string;
-    let unit = text.substring(text.length - 2).toLowerCase();
-    let valueText = '';
-    if (unitToPixels.hasOwnProperty(unit)) {
-      valueText = text.substring(0, text.length - 2);
-    } else {
-      // In case of unknown unit try to parse the whole parameter as number of pixels.
-      // This is consistent with phantom's paperSize behavior.
-      unit = 'px';
-      valueText = text;
-    }
-    const value = Number(valueText);
-    assert(!isNaN(value), 'Failed to parse parameter value: ' + text);
-    pixels = value * unitToPixels[unit];
-  } else {
-    throw new Error('page.pdf() Cannot handle parameter type: ' + (typeof parameter));
-  }
-  return pixels / 96;
-}
-
 type NetworkCookie = {
   name: string,
   value: string,
@@ -599,19 +526,6 @@ type NetworkCookie = {
   sameSite?: 'Strict'|'Lax'|'Extended'|'None'
 };
 
-type NetworkCookieParam = {
-  name: string,
-  value: string,
-  url?: string,
-  domain?: string,
-  path?: string,
-  expires?: number,
-  httpOnly?: boolean,
-  secure?: boolean,
-  sameSite?: 'Strict'|'Lax'
-};
-
-
 type DeleteNetworkCookieParam = {
   name: string,
   url?: string,
diff --git a/src/webkit/Target.ts b/src/webkit/Target.ts
index ea75d2b672b65..c40ab8edc0eae 100644
--- a/src/webkit/Target.ts
+++ b/src/webkit/Target.ts
@@ -15,13 +15,10 @@
  * limitations under the License.
  */
 
+import { helper, RegisteredListener } from '../helper';
 import { Browser, BrowserContext } from './Browser';
-import { TargetSession, Connection } from './Connection';
-import { Events } from '../Events';
-import { Page, Viewport } from './Page';
-import { TaskQueue } from './TaskQueue';
+import { Page } from './Page';
 import { Protocol } from './protocol';
-import { helper, RegisteredListener } from '../helper';
 
 export class Target {
   private _browserContext: BrowserContext;
diff --git a/src/webkit/protocolHelper.ts b/src/webkit/protocolHelper.ts
index 5ff3def3a76af..fc7ddf4c8c3c2 100644
--- a/src/webkit/protocolHelper.ts
+++ b/src/webkit/protocolHelper.ts
@@ -14,15 +14,11 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-import * as fs from 'fs';
-import {helper, assert, debugError} from '../helper';
+
+import { assert, debugError } from '../helper';
 import { TargetSession } from './Connection';
 import { Protocol } from './protocol';
 
-const openAsync = helper.promisify(fs.open);
-const writeAsync = helper.promisify(fs.write);
-const closeAsync = helper.promisify(fs.close);
-
 export function valueFromRemoteObject(remoteObject: Protocol.Runtime.RemoteObject): any {
   assert(!remoteObject.objectId, 'Cannot extract value when objectId is given');
   if (remoteObject.type === 'number') {