[proxies] Make Array.isArray respect 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 1679 matching lines @@
 function ArrayFill(value, start, end) {
   CHECK_OBJECT_COERCIBLE(this, "Array.prototype.fill");
 
   var array = TO_OBJECT(this);
   var length = TO_LENGTH_OR_UINT32(array.length);
 
   return InnerArrayFill(value, start, end, array, length);
 }
 
 
-// ES5, 15.4.3.2
-function ArrayIsArray(obj) {
-  return IS_ARRAY(obj);
-}
-
-
 function AddArrayElement(constructor, array, i, value) {
   if (constructor === GlobalArray) {
     AddIndexedProperty(array, i, value);
   } else {
     ObjectDefineProperty(array, i, {
       value: value, writable: true, configurable: true, enumerable: true
     });
   }
 }
 
@@ skipping 93 matching lines @@
   keys: true,
 };
 
 %AddNamedProperty(GlobalArray.prototype, unscopablesSymbol, unscopables,
                   DONT_ENUM | READ_ONLY);
 
 %FunctionSetLength(ArrayFrom, 1);
 
 // Set up non-enumerable functions on the Array object.
 utils.InstallFunctions(GlobalArray, DONT_ENUM, [
-  "isArray", ArrayIsArray,
   "from", ArrayFrom,
   "of", ArrayOf
 ]);
 
 var specialFunctions = %SpecialArrayFunctions();
 
 var getFunction = function(name, jsBuiltin, len) {
   var f = jsBuiltin;
   if (specialFunctions.hasOwnProperty(name)) {
     f = specialFunctions[name];
@@ skipping 99 matching lines @@
 %InstallToContext([
   "array_pop", ArrayPop,
   "array_push", ArrayPush,
   "array_shift", ArrayShift,
   "array_splice", ArraySplice,
   "array_slice", ArraySlice,
   "array_unshift", ArrayUnshift,
 ]);
 
 });