Simplify PrepareForDataProperty in the IsElement case

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 677 matching lines @@
 
 bool Object::IsJSReceiver() const {
   STATIC_ASSERT(LAST_JS_RECEIVER_TYPE == LAST_TYPE);
   return IsHeapObject() &&
       HeapObject::cast(this)->map()->instance_type() >= FIRST_JS_RECEIVER_TYPE;
 }
 
 
 bool Object::IsJSObject() const {
   STATIC_ASSERT(LAST_JS_OBJECT_TYPE == LAST_TYPE);
-  return IsHeapObject() &&
-      HeapObject::cast(this)->map()->instance_type() >= FIRST_JS_OBJECT_TYPE;
+  return IsHeapObject() && HeapObject::cast(this)->map()->IsJSObjectMap();
 }
 
 
 bool Object::IsJSProxy() const {
   if (!Object::IsHeapObject()) return false;
   return  HeapObject::cast(this)->map()->IsJSProxyMap();
 }
 
 
 TYPE_CHECKER(JSFunctionProxy, JS_FUNCTION_PROXY_TYPE)
@@ skipping 6587 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_