Support rest element pattern with user-defined iterable

src/js/runtime.js

 // Copyright 2006-2008 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.
 
 // This files contains runtime support implemented in JavaScript.
 
 // CAUTION: Some of the functions specified in this file are called
 // directly from compiled code. These are the functions with names in
 // ALL CAPS. The compiled code passes the first argument in 'this'.
 
 
 // The following declarations are shared with other native JS files.
 // They are all declared at this one spot to avoid redeclaration errors.
 
 (function(global, utils) {
 
 %CheckIsBootstrapping();
 
 var FLAG_harmony_species;
 var GlobalArray = global.Array;
 var GlobalBoolean = global.Boolean;
 var GlobalString = global.String;
 var MakeRangeError;
 var MakeTypeError;
 var speciesSymbol;
+var iteratorSymbol
 
 utils.Import(function(from) {
   MakeRangeError = from.MakeRangeError;
   MakeTypeError = from.MakeTypeError;
   speciesSymbol = from.species_symbol;
+  iteratorSymbol = from.iterator_symbol;
 });
 
 utils.ImportFromExperimental(function(from) {
   FLAG_harmony_species = from.FLAG_harmony_species;
 });
 
 // ----------------------------------------------------------------------------
 
 /* -------------------------------------
    - - -   C o n v e r s i o n s   - - -
@@ skipping 19 matching lines @@
 function SameValueZero(x, y) {
   if (typeof x !== typeof y) return false;
   if (IS_NUMBER(x)) {
     if (NUMBER_IS_NAN(x) && NUMBER_IS_NAN(y)) return true;
   }
   if (IS_SIMD_VALUE(x)) return %SimdSameValueZero(x, y);
   return x === y;
 }
 
 
-function ConcatIterableToArray(target, iterable) {
+function ConcatIteratorToArray(target, iterator) {
    var index = target.length;
+   var iterable = { [iteratorSymbol]() { return iterator; } };
    for (var element of iterable) {
      AddIndexedProperty(target, index++, element);
    }
    return target;
 }
 
 
 /* ---------------------------------
    - - -   U t i l i t i e s   - - -
    ---------------------------------
@@ skipping 82 matching lines @@
   to.AddIndexedProperty = AddIndexedProperty;
   to.MaxSimple = MaxSimple;
   to.MinSimple = MinSimple;
   to.SameValue = SameValue;
   to.SameValueZero = SameValueZero;
   to.ToPositiveInteger = ToPositiveInteger;
   to.SpeciesConstructor = SpeciesConstructor;
 });
 
 %InstallToContext([
-  "concat_iterable_to_array", ConcatIterableToArray,
+  "concat_iterator_to_array", ConcatIteratorToArray,
 ]);
 
 })