[es6] Move builtin constructors for primitives to strict mode.

src/symbol.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.
 
 (function(global, utils) {
 
 "use strict";
 
 %CheckIsBootstrapping();
 
@@ skipping 14 matching lines @@
 var unscopablesSymbol = utils.ImportNow("unscopables_symbol");
 
 utils.Import(function(from) {
   ObjectGetOwnPropertyKeys = from.ObjectGetOwnPropertyKeys;
   ToString = from.ToString;
 });
 
 // -------------------------------------------------------------------
 
 function SymbolConstructor(x) {
+  "use strict";

[Michael Starzinger, 2015/09/15 13:09:58]

The entire module is already strict, let's drop it.

   if (%_IsConstructCall()) throw MakeTypeError(kNotConstructor, "Symbol");
   // NOTE: Passing in a Symbol value will throw on ToString().
   return %CreateSymbol(IS_UNDEFINED(x) ? x : ToString(x));
 }
 
 
 // 19.4.3.4 Symbol.prototype [ @@toPrimitive ] ( hint )
 function SymbolToPrimitive(hint) {
   if (!(IS_SYMBOL(this) || IS_SYMBOL_WRAPPER(this))) {
     throw MakeTypeError(kIncompatibleMethodReceiver,
@@ skipping 91 matching lines @@
 ]);
 
 // -------------------------------------------------------------------
 // Exports
 
 utils.Export(function(to) {
   to.SymbolToString = SymbolToString;
 })
 
 })