Refactor copying of maps and descriptor arrays.

src/heap.cc

 // 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 4162 matching lines @@
   }
 
   // Allocate the global object and initialize it with the backing store.
   { MaybeObject* maybe_obj = Allocate(map, OLD_POINTER_SPACE);
     if (!maybe_obj->ToObject(&obj)) return maybe_obj;
   }
   JSObject* global = JSObject::cast(obj);
   InitializeJSObjectFromMap(global, dictionary, map);
 
   // Create a new map for the global object.
-  { MaybeObject* maybe_obj = map->CopyDropDescriptors();
-    if (!maybe_obj->ToObject(&obj)) return maybe_obj;
+  Map* new_map;
+  { MaybeObject* maybe_map = map->CopyDropDescriptors();
+    if (!maybe_map->To(&new_map)) return maybe_map;
   }
-  Map* new_map = Map::cast(obj);
 
   // Set up the global object as a normalized object.
   global->set_map(new_map);
   global->set_properties(dictionary);
 
   // Make sure result is a global object with properties in dictionary.
   ASSERT(global->IsGlobalObject());
   ASSERT(!global->HasFastProperties());
   return global;
 }
@@ skipping 3022 matching lines @@
   } else {
     p ^= 0x1d1ed & (Page::kPageSize - 1);  // I died.
   }
   remembered_unmapped_pages_[remembered_unmapped_pages_index_] =
       reinterpret_cast<Address>(p);
   remembered_unmapped_pages_index_++;
   remembered_unmapped_pages_index_ %= kRememberedUnmappedPages;
 }
 
 } }  // namespace v8::internal