Wrap runtime.js in a function.

src/string-iterator.js

 // Copyright 2014 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() {
 
 "use strict";
 
 %CheckIsBootstrapping();
 
@@ skipping 21 matching lines @@
 
 
 // 21.1.5.2.2 %StringIteratorPrototype%[@@iterator]
 function StringIteratorIterator() {
   return this;
 }
 
 
 // 21.1.5.2.1 %StringIteratorPrototype%.next( )
 function StringIteratorNext() {
-  var iterator = ToObject(this);
+  var iterator = $toObject(this);
 
   if (!HAS_DEFINED_PRIVATE(iterator, stringIteratorNextIndexSymbol)) {
     throw MakeTypeError(kIncompatibleMethodReceiver,
                         'String Iterator.prototype.next');
   }
 
   var s = GET_PRIVATE(iterator, stringIteratorIteratedStringSymbol);
   if (IS_UNDEFINED(s)) {
     return $iteratorCreateResultObject(UNDEFINED, true);
   }
@@ skipping 42 matching lines @@
 %AddNamedProperty(StringIterator.prototype, symbolIterator,
                   StringIteratorIterator, DONT_ENUM);
 %AddNamedProperty(StringIterator.prototype, symbolToStringTag,
                   "String Iterator", READ_ONLY | DONT_ENUM);
 
 $setFunctionName(StringPrototypeIterator, symbolIterator);
 %AddNamedProperty(GlobalString.prototype, symbolIterator,
                   StringPrototypeIterator, DONT_ENUM);
 
 })();