[es6] Initial steps towards a correct implementation of IsCallable.

src/weak-collection.js

 // Copyright 2012 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.
 
 (function(global, utils) {
 
 "use strict";
 
 %CheckIsBootstrapping();
 
 var GlobalObject = global.Object;
 var GlobalWeakMap = global.WeakMap;
 var GlobalWeakSet = global.WeakSet;
 var toStringTagSymbol = utils.ImportNow("to_string_tag_symbol");
 
 // -------------------------------------------------------------------
 // Harmony WeakMap
 
 function WeakMapConstructor(iterable) {
   if (!%_IsConstructCall()) {
     throw MakeTypeError(kConstructorNotFunction, "WeakMap");
   }
 
   %WeakCollectionInitialize(this);
 
   if (!IS_NULL_OR_UNDEFINED(iterable)) {
     var adder = this.set;
-    if (!IS_SPEC_FUNCTION(adder)) {
+    if (!IS_CALLABLE(adder)) {
       throw MakeTypeError(kPropertyNotFunction, 'set', this);
     }
     for (var nextItem of iterable) {
       if (!IS_SPEC_OBJECT(nextItem)) {
         throw MakeTypeError(kIteratorValueNotAnObject, nextItem);
       }
       %_CallFunction(this, nextItem[0], nextItem[1], adder);
     }
   }
 }
@@ skipping 68 matching lines @@
 
 function WeakSetConstructor(iterable) {
   if (!%_IsConstructCall()) {
     throw MakeTypeError(kConstructorNotFunction, "WeakSet");
   }
 
   %WeakCollectionInitialize(this);
 
   if (!IS_NULL_OR_UNDEFINED(iterable)) {
     var adder = this.add;
-    if (!IS_SPEC_FUNCTION(adder)) {
+    if (!IS_CALLABLE(adder)) {
       throw MakeTypeError(kPropertyNotFunction, 'add', this);
     }
     for (var value of iterable) {
       %_CallFunction(this, value, adder);
     }
   }
 }
 
 
 function WeakSetAdd(value) {
@@ skipping 41 matching lines @@
                   DONT_ENUM | READ_ONLY);
 
 // Set up the non-enumerable functions on the WeakSet prototype object.
 utils.InstallFunctions(GlobalWeakSet.prototype, DONT_ENUM, [
   "add", WeakSetAdd,
   "has", WeakSetHas,
   "delete", WeakSetDelete
 ]);
 
 })