Simplify GetEnumPropertyKeys and avoid trimming fixed arrays in large object space.

src/objects.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 3998 matching lines @@
 
 
 class NameDictionary: public Dictionary<NameDictionaryShape, Name*> {
  public:
   static inline NameDictionary* cast(Object* obj) {
     ASSERT(obj->IsDictionary());
     return reinterpret_cast<NameDictionary*>(obj);
   }
 
   // Copies enumerable keys to preallocated fixed array.
-  FixedArray* CopyEnumKeysTo(FixedArray* storage);
+  void CopyEnumKeysTo(FixedArray* storage);
   static void DoGenerateNewEnumerationIndices(
       Handle<NameDictionary> dictionary);
 
   // For transforming properties of a JSObject.
   MUST_USE_RESULT MaybeObject* TransformPropertiesToFastFor(
       JSObject* obj,
       int unused_property_fields);
 
   // Find entry for key, otherwise return kNotFound. Optimized version of
   // HashTable::FindEntry.
@@ skipping 6729 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_