[proxies] Make Array.isArray respect proxies.

src/objects.cc

 // 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.
 
 #include "src/objects.h"
 
 #include <cmath>
 #include <iomanip>
 #include <sstream>
 
@@ skipping 593 matching lines @@
                       Object);
     }
     ASSIGN_RETURN_ON_EXCEPTION(isolate, lhs, Object::ToNumber(lhs), Object);
     ASSIGN_RETURN_ON_EXCEPTION(isolate, rhs, Object::ToNumber(rhs), Object);
   }
   return isolate->factory()->NewNumberFromInt(NumberToInt32(*lhs) ^
                                               NumberToInt32(*rhs));
 }
 
 
+Maybe<bool> Object::IsArray(Handle<Object> object) {
+  if (object->IsJSArray()) return Just(true);
+  if (object->IsJSProxy()) {
+    Handle<JSProxy> proxy = Handle<JSProxy>::cast(object);
+    Isolate* isolate = proxy->GetIsolate();
+    if (proxy->IsRevoked()) {
+      isolate->Throw(*isolate->factory()->NewTypeError(
+          MessageTemplate::kProxyRevoked,
+          isolate->factory()->NewStringFromAsciiChecked("IsArray")));
+      return Nothing<bool>();
+    }
+    return Object::IsArray(handle(proxy->target(), isolate));
+  }
+  return Just(false);
+}
+
+
 bool Object::IsPromise(Handle<Object> object) {
   if (!object->IsJSObject()) return false;
   auto js_object = Handle<JSObject>::cast(object);
   // Promises can't have access checks.
   if (js_object->map()->is_access_check_needed()) return false;
   auto isolate = js_object->GetIsolate();
   // TODO(dcarney): this should just be read from the symbol registry so as not
   // to be context dependent.
   auto key = isolate->factory()->promise_status_symbol();
   // Shouldn't be possible to throw here.
@@ skipping 352 matching lines @@
     THROW_NEW_ERROR(isolate,
                     NewTypeError(MessageTemplate::kProxyHandlerTrapMissing,
                                  handler, trap_name),
                     Object);
   }
   // 13. Return handlerProto.
   return handler_proto;
 }
 
 
-bool JSProxy::IsRevoked() {
+bool JSProxy::IsRevoked() const {
   // TODO(neis): Decide on how to represent revocation.  For now, revocation is
   // unsupported.
   DCHECK(target()->IsJSReceiver());
   DCHECK(handler()->IsJSReceiver());
   return false;
 }
 
 
 MaybeHandle<Object> Object::GetPropertyWithAccessor(
     LookupIterator* it, LanguageMode language_mode) {
@@ skipping 18058 matching lines @@
   if (cell->value() != *new_value) {
     cell->set_value(*new_value);
     Isolate* isolate = cell->GetIsolate();
     cell->dependent_code()->DeoptimizeDependentCodeGroup(
         isolate, DependentCode::kPropertyCellChangedGroup);
   }
 }
 
 }  // namespace internal
 }  // namespace v8