fix(parser): dedupe some code

package.json

@@ -1,6 +1,6 @@
 {
   "name": "meriyah",
-  "version": "0.2.10",
+  "version": "0.2.12",
   "description": "A 100% compliant, self-hosted javascript parser with high focus on both performance and stability",
   "main": "dist/meriyah.umd.js",
   "module": "dist/meriyah.esm.js",
@@ -60,17 +60,17 @@
     "post_coverage": "cross-env cat ./coverage/lcov.info | coveralls"
   },
   "devDependencies": {
-    "@types/mocha": "^5.2.6",
-    "@types/node": "^12.0.2",
-    "coveralls": "^3.0.3",
+    "@types/mocha": "^5.2.7",
+    "@types/node": "^12.0.7",
+    "coveralls": "^3.0.4",
     "cross-env": "^5.2.0",
-    "husky": "^2.3.0",
+    "husky": "^2.4.0",
     "mocha": "^6.1.4",
     "nyc": "^14.1.1",
     "path": "^0.12.7",
-    "prettier": "^1.17.1",
+    "prettier": "^1.18.2",
     "rimraf": "^2.6.3",
-    "rollup": "^1.13.0",
+    "rollup": "^1.14.4",
     "rollup-plugin-replace": "^2.2.0",
     "rollup-plugin-terser": "^5.0.0",
     "rollup-plugin-typescript2": "^0.21.1",

src/common.ts

@@ -79,7 +79,9 @@ export const enum BindingOrigin {
 export const enum AssignmentKind {
   None           = 0,
   IsAssignable   = 1 << 0,
-  CannotAssign   = 1 << 1
+  CannotAssign   = 1 << 1,
+  Await          = 1 << 2,
+  Yield          = 1 << 3,
 }
 
 export const enum DestructuringKind {
@@ -102,7 +104,8 @@ export const enum Flags {
   NewLine             = 1 << 0,
   HasConstructor      = 1 << 5,
   Octals              = 1 << 6,
-  SimpleParameterList = 1 << 7
+  SimpleParameterList = 1 << 7,
+  Yield          = 1 << 8,
 }
 
 export const enum FunctionStatement {
@@ -242,7 +245,8 @@ export function validateBindingIdentifier(
   parser: ParserState,
   context: Context,
   type: BindingType,
-  t: Token
+  t: Token,
+  skipEvalArgCheck: 0 | 1
 ): void {
   if ((t & Token.Keyword) !== Token.Keyword) return;
 
@@ -255,7 +259,7 @@ export function validateBindingIdentifier(
       report(parser, Errors.FutureReservedWordInStrictModeNotId);
     }
 
-    if ((t & Token.IsEvalOrArguments) === Token.IsEvalOrArguments) {
+    if (!skipEvalArgCheck && (t & Token.IsEvalOrArguments) === Token.IsEvalOrArguments) {
       report(parser, Errors.StrictEvalArguments);
     }