In Array.of and Array.from, fall back to DefineOwnProperty

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.
 
 (function(global, utils) {
 
 'use strict';
 
 %CheckIsBootstrapping();
 
 // -------------------------------------------------------------------
 // Imports
 
 var GlobalArray = global.Array;
 var GlobalSymbol = global.Symbol;
 
 var GetIterator;
 var GetMethod;
 var MathMax;
 var MathMin;
 var ObjectIsFrozen;
+var ObjectDefineProperty;
 
 utils.Import(function(from) {
   GetIterator = from.GetIterator;
   GetMethod = from.GetMethod;
   MathMax = from.MathMax;
   MathMin = from.MathMin;
   ObjectIsFrozen = from.ObjectIsFrozen;
+  ObjectDefineProperty = from.ObjectDefineProperty;
 });
 
 // -------------------------------------------------------------------
 
 function InnerArrayCopyWithin(target, start, end, array, length) {
   target = TO_INTEGER(target);
   var to;
   if (target < 0) {
     to = MathMax(length + target, 0);
   } else {
@@ skipping 145 matching lines @@
 // ES6, draft 04-05-14, section 22.1.3.6
 function ArrayFill(value, start, end) {
   CHECK_OBJECT_COERCIBLE(this, "Array.prototype.fill");
 
   var array = $toObject(this);
   var length = TO_UINT32(array.length);
 
   return InnerArrayFill(value, start, end, array, length);
 }
 
+function AddArrayElement(constructor, array, i, value) {
+  if (constructor === GlobalArray) {
+    %AddElement(array, i, value);
+  } else {
+    ObjectDefineProperty(array, i, {
+      value: value, writable: true, configurable: true, enumerable: true
+    });
+  }
+}
+
 // ES6, draft 10-14-14, section 22.1.2.1
 function ArrayFrom(arrayLike, mapfn, receiver) {
   var items = $toObject(arrayLike);
   var mapping = !IS_UNDEFINED(mapfn);
 
   if (mapping) {
     if (!IS_SPEC_FUNCTION(mapfn)) {
       throw MakeTypeError(kCalledNonCallable, mapfn);
     } else if (%IsSloppyModeFunction(mapfn)) {
       if (IS_NULL(receiver)) {
@@ skipping 27 matching lines @@
         result.length = k;
         return result;
       }
 
       nextValue = next.value;
       if (mapping) {
         mappedValue = %_CallFunction(receiver, nextValue, k, mapfn);
       } else {
         mappedValue = nextValue;
       }
-      // TODO(verwaest): This should redefine rather than adding.
-      %AddElement(result, k++, mappedValue);
+      AddArrayElement(this, result, k, mappedValue);
+      k++;
     }
   } else {
     var len = $toLength(items.length);
     result = %IsConstructor(this) ? new this(len) : new GlobalArray(len);
 
     for (k = 0; k < len; ++k) {
       nextValue = items[k];
       if (mapping) {
         mappedValue = %_CallFunction(receiver, nextValue, k, mapfn);
       } else {
         mappedValue = nextValue;
       }
-      // TODO(verwaest): This should redefine rather than adding.
-      %AddElement(result, k, mappedValue);
+      AddArrayElement(this, result, k, mappedValue);
     }
 
     result.length = k;
     return result;
   }
 }
 
 // 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++) {
-    // TODO(verwaest): This should redefine rather than adding.
-    %AddElement(array, i, %_Arguments(i));
+    AddArrayElement(constructor, array, i, %_Arguments(i));
   }
   array.length = length;
   return array;
 }
 
 // -------------------------------------------------------------------
 
 utils.InstallConstants(GlobalSymbol, [
   // TODO(dslomov, caitp): Move to symbol.js when shipping
   "isConcatSpreadable", symbolIsConcatSpreadable
@@ skipping 24 matching lines @@
 
 utils.Export(function(to) {
   to.ArrayFrom = ArrayFrom;
   to.InnerArrayCopyWithin = InnerArrayCopyWithin;
   to.InnerArrayFill = InnerArrayFill;
   to.InnerArrayFind = InnerArrayFind;
   to.InnerArrayFindIndex = InnerArrayFindIndex;
 });
 
 })