[runtime] Don't call GetArrayKeys on proxies.

src/js/array.js

 // Copyright 2012 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, extrasUtils) {
 
 "use strict";
 
 %CheckIsBootstrapping();
 
@@ skipping 1031 matching lines @@
       }
     }
   };
 
   // Copy elements in the range 0..length from obj's prototype chain
   // to obj itself, if obj has holes. Return one more than the maximal index
   // of a prototype property.
   var CopyFromPrototype = function CopyFromPrototype(obj, length) {
     var max = 0;
     for (var proto = %_GetPrototype(obj); proto; proto = %_GetPrototype(proto)) {
-      var indices = %GetArrayKeys(proto, length);
+      var indices = IS_PROXY(proto) ? length : %GetArrayKeys(proto, length);

[Camillo Bruni, 2016/03/29 11:34:57]

aah quelle elegance!

       if (IS_NUMBER(indices)) {
         // It's an interval.
         var proto_length = indices;
         for (var i = 0; i < proto_length; i++) {
           if (!HAS_OWN_PROPERTY(obj, i) && HAS_OWN_PROPERTY(proto, i)) {
             obj[i] = proto[i];
             if (i >= max) { max = i + 1; }
           }
         }
       } else {
         for (var i = 0; i < indices.length; i++) {
           var index = indices[i];
           if (!HAS_OWN_PROPERTY(obj, index) && HAS_OWN_PROPERTY(proto, index)) {
             obj[index] = proto[index];
             if (index >= max) { max = index + 1; }
           }
         }
       }
     }
     return max;
   };
 
   // Set a value of "undefined" on all indices in the range from..to
   // where a prototype of obj has an element. I.e., shadow all prototype
   // elements in that range.
   var ShadowPrototypeElements = function(obj, from, to) {
     for (var proto = %_GetPrototype(obj); proto; proto = %_GetPrototype(proto)) {
-      var indices = %GetArrayKeys(proto, to);
+      var indices = IS_PROXY(proto) ? to : %GetArrayKeys(proto, to);
       if (IS_NUMBER(indices)) {
         // It's an interval.
         var proto_length = indices;
         for (var i = from; i < proto_length; i++) {
           if (HAS_OWN_PROPERTY(proto, i)) {
             obj[i] = UNDEFINED;
           }
         }
       } else {
         for (var i = 0; i < indices.length; i++) {
@@ skipping 864 matching lines @@
 %InstallToContext([
   "array_pop", ArrayPop,
   "array_push", ArrayPush,
   "array_shift", ArrayShift,
   "array_splice", ArraySplice,
   "array_slice", ArraySlice,
   "array_unshift", ArrayUnshift,
 ]);
 
 });