[runtime] Support Proxy setPrototypeOf trap

src/runtime/runtime-object.cc

 // Copyright 2014 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/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/bootstrapper.h"
 #include "src/debug/debug.h"
 #include "src/isolate-inl.h"
@@ skipping 164 matching lines @@
       isolate->heap()->exception());
   return *obj;
 }
 
 
 RUNTIME_FUNCTION(Runtime_SetPrototype) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 2);
   CONVERT_ARG_HANDLE_CHECKED(JSReceiver, obj, 0);
   CONVERT_ARG_HANDLE_CHECKED(Object, prototype, 1);
-  MAYBE_RETURN(
-      JSReceiver::SetPrototype(obj, prototype, true, Object::THROW_ON_ERROR),
-      isolate->heap()->exception());
+
+  Maybe<bool> status =
+      JSReceiver::SetPrototype(obj, prototype, true, Object::THROW_ON_ERROR);
+  if (status.IsNothing()) return isolate->heap()->exception();
+  if (!status.FromJust()) {

[Camillo Bruni, 2015/11/16 13:32:08]

We should probably throw the error already in JSProxy::SetPrototype in case the
trap return false, thus allowing for a more specific error message.

+    THROW_NEW_ERROR_RETURN_FAILURE(
+        isolate, NewTypeError(MessageTemplate::kObjectSetPrototypeFailed, obj,
+                              prototype));
+  }
   return *obj;
 }
 
 
 // Enumerator used as indices into the array returned from GetOwnProperty
 enum PropertyDescriptorIndices {
   IS_ACCESSOR_INDEX,
   VALUE_INDEX,
   GETTER_INDEX,
   SETTER_INDEX,
@@ skipping 1370 matching lines @@
 
 RUNTIME_FUNCTION(Runtime_ObjectDefineProperties) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 2);
   CONVERT_ARG_HANDLE_CHECKED(Object, o, 0);
   CONVERT_ARG_HANDLE_CHECKED(Object, properties, 1);
   return JSReceiver::DefineProperties(isolate, o, properties);
 }
 }  // namespace internal
 }  // namespace v8