Move some code from Runtime_GetPrototype into a new Object::GetPrototype.

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 139 matching lines @@
 
   return Object::SetProperty(&it, value, language_mode,
                              Object::MAY_BE_STORE_FROM_KEYED);
 }
 
 
 RUNTIME_FUNCTION(Runtime_GetPrototype) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(Object, obj, 0);
-  // We don't expect access checks to be needed on JSProxy objects.
-  DCHECK(!obj->IsAccessCheckNeeded() || obj->IsJSObject());
-  PrototypeIterator iter(isolate, obj, PrototypeIterator::START_AT_RECEIVER);
-  Handle<Context> context(isolate->context());
-  do {
-    if (PrototypeIterator::GetCurrent(iter)->IsAccessCheckNeeded() &&
-        !isolate->MayAccess(context,
-                            PrototypeIterator::GetCurrent<JSObject>(iter))) {
-      return isolate->heap()->null_value();
-    }
-    iter.AdvanceIgnoringProxies();
-    if (PrototypeIterator::GetCurrent(iter)->IsJSProxy()) {
-      return *PrototypeIterator::GetCurrent(iter);
-    }
-  } while (!iter.IsAtEnd(PrototypeIterator::END_AT_NON_HIDDEN));
-  return *PrototypeIterator::GetCurrent(iter);
+  return *Object::GetPrototype(isolate, obj);
 }
 
 
 RUNTIME_FUNCTION(Runtime_InternalSetPrototype) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 2);
   CONVERT_ARG_HANDLE_CHECKED(JSObject, obj, 0);
   CONVERT_ARG_HANDLE_CHECKED(Object, prototype, 1);
   Handle<Object> result;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
@@ skipping 1402 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