Fix uninitialized variable compiler errors [GCC 4.8.4]

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 1856 matching lines @@
         TransitionElementsKind(object, FAST_HOLEY_DOUBLE_ELEMENTS);
         return;
       }
     }
     TransitionElementsKind(object, FAST_DOUBLE_ELEMENTS);
   }
 }
 
 
 bool JSObject::WouldConvertToSlowElements(Handle<Object> key) {
-  uint32_t index;
+  uint32_t index = 0;
   return key->ToArrayIndex(&index) && WouldConvertToSlowElements(index);
 }
 
 
 void JSObject::SetMapAndElements(Handle<JSObject> object,
                                  Handle<Map> new_map,
                                  Handle<FixedArrayBase> value) {
   JSObject::MigrateToMap(object, new_map);
   DCHECK((object->map()->has_fast_smi_or_object_elements() ||
           (*value == object->GetHeap()->empty_fixed_array())) ==
@@ skipping 5860 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_