fix(@angular/cli): shut down after first Ctrl+C received

Fixes #9647

Author: devoto13

packages/@ngtools/webpack/package.json

@@ -25,7 +25,6 @@
     "npm": ">= 3.0.0"
   },
   "dependencies": {
-    "tree-kill": "^1.0.0",
     "chalk": "~2.2.0",
     "loader-utils": "^1.0.2",
     "enhanced-resolve": "^3.1.0",

packages/@ngtools/webpack/src/angular_compiler_plugin.ts

@@ -5,7 +5,6 @@ import * as path from 'path';
 import * as ts from 'typescript';
 
 const ContextElementDependency = require('webpack/lib/dependencies/ContextElementDependency');
-const treeKill = require('tree-kill');
 
 import { WebpackResourceLoader } from './resource_loader';
 import { WebpackCompilerHost } from './compiler_host';
@@ -507,29 +506,11 @@ export class AngularCompilerPlugin implements Tapable {
       forkOptions);
 
     // Handle child process exit.
-    const handleChildProcessExit = () => {
-      this._killForkedTypeChecker();
+    this._typeCheckerProcess.on('exit', () => {
       const msg = 'AngularCompilerPlugin: Forked Type Checker exited unexpectedly. ' +
         'Falling back to type checking on main thread.';
       this._warnings.push(msg);
-    };
-    this._typeCheckerProcess.once('exit', handleChildProcessExit);
-    this._typeCheckerProcess.once('SIGINT', handleChildProcessExit);
-    this._typeCheckerProcess.once('uncaughtException', handleChildProcessExit);
-
-    // Handle parent process exit.
-    const handleParentProcessExit = () => this._killForkedTypeChecker();
-    process.once('exit', handleParentProcessExit);
-    process.once('SIGINT', handleParentProcessExit);
-    process.once('uncaughtException', handleParentProcessExit);
-  }
-
-  private _killForkedTypeChecker() {
-    if (this._typeCheckerProcess && this._typeCheckerProcess.pid) {
-      treeKill(this._typeCheckerProcess.pid, 'SIGTERM');
-      this._typeCheckerProcess = undefined;
-      this._forkTypeChecker = false;
-    }
+    });
   }
 
   private _updateForkedTypeChecker(rootNames: string[], changedCompilationFiles: string[]) {
@@ -618,7 +599,6 @@ export class AngularCompilerPlugin implements Tapable {
       }
       callback();
     });
-    compiler.plugin('watch-close', () => this._killForkedTypeChecker());
 
     // Remake the plugin on each compilation.
     compiler.plugin('make', (compilation: any, cb: any) => this._make(compilation, cb));