Add TypedArray.from method

src/harmony-array.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.
 
 var $innerArrayCopyWithin;
 var $innerArrayFill;
 var $innerArrayFind;
 var $innerArrayFindIndex;
+var $arrayFrom;
 
 (function(global, exports) {
 
 'use strict';
 
 %CheckIsBootstrapping();
 
 var GlobalArray = global.Array;
 var GlobalSymbol = global.Symbol;
 
@@ skipping 228 matching lines @@
       } else {
         mappedValue = nextValue;
       }
       %AddElement(result, k, mappedValue, NONE);
     }
 
     result.length = k;
     return result;
   }
 }
+$arrayFrom = ArrayFrom;
 
 // ES6, draft 05-22-14, section 22.1.2.3
 function ArrayOf() {
   var length = %_ArgumentsLength();
   var constructor = this;
   // TODO: Implement IsConstructor (ES6 section 7.2.5)
   var array = %IsConstructor(constructor) ? new constructor(length) : [];
   for (var i = 0; i < length; i++) {
     %AddElement(array, i, %_Arguments(i), NONE);
   }
@@ skipping 22 matching lines @@
 
 // Set up the non-enumerable functions on the Array prototype object.
 $installFunctions(GlobalArray.prototype, DONT_ENUM, [
   "copyWithin", ArrayCopyWithin,
   "find", ArrayFind,
   "findIndex", ArrayFindIndex,
   "fill", ArrayFill
 ]);
 
 })