Get rid of ConvertFieldToDescriptor and simplify related code.

src/objects-inl.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1847 matching lines @@
   }
 }
 
 
 bool JSObject::HasFastProperties() {
   ASSERT(properties()->IsDictionary() == map()->is_dictionary_map());
   return !properties()->IsDictionary();
 }
 
 
-bool JSObject::TooManyFastProperties(int properties,
-                                     JSObject::StoreFromKeyed store_mode) {
+bool JSObject::TooManyFastProperties(StoreFromKeyed store_mode) {
   // Allow extra fast properties if the object has more than
-  // kFastPropertiesSoftLimit in-object properties. When this is the case,
-  // it is very unlikely that the object is being used as a dictionary
-  // and there is a good chance that allowing more map transitions
-  // will be worth it.
-  int inobject = map()->inobject_properties();
+  // kFastPropertiesSoftLimit in-object properties. When this is the case, it is
+  // very unlikely that the object is being used as a dictionary and there is a
+  // good chance that allowing more map transitions will be worth it.
+  Map* map = this->map();
+  if (map->unused_property_fields() != 0) return false;
+
+  int inobject = map->inobject_properties();
 
   int limit;
   if (store_mode == CERTAINLY_NOT_STORE_FROM_KEYED) {
     limit = Max(inobject, kMaxFastProperties);
   } else {
     limit = Max(inobject, kFastPropertiesSoftLimit);
   }
-  return properties > limit;
+  return properties()->length() > limit;
 }
 
 
 void Struct::InitializeBody(int object_size) {
   Object* value = GetHeap()->undefined_value();
   for (int offset = kHeaderSize; offset < object_size; offset += kPointerSize) {
     WRITE_FIELD(this, offset, value);
   }
 }
 
@@ skipping 4364 matching lines @@
 #undef WRITE_UINT32_FIELD
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_