Make JSProxies always be in slow mode

src/objects-inl.h

 // 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.
 //
 // Review notes:
 //
 // - The use of macros in these inline functions may seem superfluous
 // but it is absolutely needed to make sure gcc generates optimal
 // code. gcc is not happy when attempting to inline too deep.
 //
@@ skipping 7049 matching lines @@
                                                  Handle<Object> receiver,
                                                  LanguageMode language_mode) {
   LookupIterator it = LookupIterator::PropertyOrElement(
       name->GetIsolate(), receiver, name, holder);
   return GetProperty(&it, language_mode);
 }
 
 
 void JSReceiver::initialize_properties() {
   DCHECK(!GetHeap()->InNewSpace(GetHeap()->empty_fixed_array()));
-  WRITE_FIELD(this, kPropertiesOffset, GetHeap()->empty_fixed_array());
+  DCHECK(!GetHeap()->InNewSpace(GetHeap()->empty_properties_dictionary()));
+  if (map()->is_dictionary_map()) {
+    WRITE_FIELD(this, kPropertiesOffset,
+                GetHeap()->empty_properties_dictionary());
+  } else {
+    WRITE_FIELD(this, kPropertiesOffset, GetHeap()->empty_fixed_array());
+  }
 }
 
 
 bool JSReceiver::HasFastProperties() {
   DCHECK(properties()->IsDictionary() == map()->is_dictionary_map());
   return !properties()->IsDictionary();
 }
 
 
 NameDictionary* JSReceiver::property_dictionary() {
@@ skipping 723 matching lines @@
 #undef WRITE_INT64_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 #undef NOBARRIER_READ_BYTE_FIELD
 #undef NOBARRIER_WRITE_BYTE_FIELD
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_OBJECTS_INL_H_