Re-implement %Generator% intrinsic as an object

src/generator.js

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 "use strict";
 
 // This file relies on the fact that the following declarations have been made
 // in runtime.js:
 // var $Function = global.Function;
 
@@ skipping 49 matching lines @@
   } else {
     // Generator is running.
     throw MakeTypeError('generator_running', []);
   }
 }
 
 function GeneratorObjectIterator() {
   return this;
 }
 
-function GeneratorFunctionPrototypeConstructor(x) {
-  if (%_IsConstructCall()) {
-    throw MakeTypeError('not_constructor', ['GeneratorFunctionPrototype']);
-  }
-}
-
 function GeneratorFunctionConstructor(arg1) {  // length == 1
   var source = NewFunctionString(arguments, 'function*');
   var global_proxy = %GlobalProxy(global);
   // Compile the string in the constructor and not a helper so that errors
   // appear to come from here.
   var f = %_CallFunction(global_proxy, %CompileString(source, true));
   %FunctionMarkNameShouldPrintAsAnonymous(f);
   return f;
 }
 
@@ skipping 16 matching lines @@
   %FunctionSetName(GeneratorObjectIterator, '[Symbol.iterator]');
   %AddNamedProperty(GeneratorObjectPrototype, symbolIterator,
       GeneratorObjectIterator, DONT_ENUM | DONT_DELETE | READ_ONLY);
   %AddNamedProperty(GeneratorObjectPrototype, "constructor",
       GeneratorFunctionPrototype, DONT_ENUM | READ_ONLY);
   %AddNamedProperty(GeneratorObjectPrototype,
       symbolToStringTag, "Generator", DONT_ENUM | READ_ONLY);
   %InternalSetPrototype(GeneratorFunctionPrototype, $Function.prototype);
   %AddNamedProperty(GeneratorFunctionPrototype,
       symbolToStringTag, "GeneratorFunction", DONT_ENUM | READ_ONLY);
-  %SetCode(GeneratorFunctionPrototype, GeneratorFunctionPrototypeConstructor);
   %AddNamedProperty(GeneratorFunctionPrototype, "constructor",
       GeneratorFunction, DONT_ENUM | READ_ONLY);
   %InternalSetPrototype(GeneratorFunction, $Function);
   %SetCode(GeneratorFunction, GeneratorFunctionConstructor);
 }
 
 SetUpGenerators();