Keep function.prototype fast.

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 2097 matching lines @@
 
 
 bool JSObject::HasFastProperties() {
   ASSERT(properties()->IsDictionary() == map()->is_dictionary_map());
   return !properties()->IsDictionary();
 }
 
 
 bool Map::TooManyFastProperties(StoreFromKeyed store_mode) {
   if (unused_property_fields() != 0) return false;
+  if (is_prototype_map()) return false;
   int minimum = store_mode == CERTAINLY_NOT_STORE_FROM_KEYED ? 128 : 12;
   int limit = Max(minimum, inobject_properties());
   int external = NumberOfFields() - inobject_properties();
   return external > limit;
 }
 
 
 void Struct::InitializeBody(int object_size) {
   Object* value = GetHeap()->undefined_value();
   for (int offset = kHeaderSize; offset < object_size; offset += kPointerSize) {
@@ skipping 2310 matching lines @@
   } else {
     set_bit_field2(bit_field2() & ~(1 << kIsExtensible));
   }
 }
 
 bool Map::is_extensible() {
   return ((1 << kIsExtensible) & bit_field2()) != 0;
 }
 
 
+void Map::mark_prototype_map() {
+  set_bit_field2(IsPrototypeMapBits::update(bit_field2(), true));
+}
+
+bool Map::is_prototype_map() {
+  return IsPrototypeMapBits::decode(bit_field2());
+}
+
+
 void Map::set_is_shared(bool value) {
   set_bit_field3(IsShared::update(bit_field3(), value));
 }
 
 
 bool Map::is_shared() {
   return IsShared::decode(bit_field3()); }
 
 
 void Map::set_dictionary_map(bool value) {
@@ skipping 2801 matching lines @@
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 #undef NOBARRIER_READ_BYTE_FIELD
 #undef NOBARRIER_WRITE_BYTE_FIELD
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_