Removed superfluous cast.

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 4776 matching lines @@
 bool String::AsArrayIndex(uint32_t* index) {
   uint32_t field = hash_field();
   if (IsHashFieldComputed(field) && (field & kIsNotArrayIndexMask)) {
     return false;
   }
   return SlowAsArrayIndex(index);
 }
 
 
 Object* JSReceiver::GetPrototype() {
-  return HeapObject::cast(this)->map()->prototype();
+  return map()->prototype();
 }
 
 
 Object* JSReceiver::GetConstructor() {
   return map()->constructor();
 }
 
 
 bool JSReceiver::HasProperty(String* name) {
   if (IsJSProxy()) {
@@ skipping 415 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_