A change in the way we place TransitionElementKinds in the tree.

src/elements-kind.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 118 matching lines @@
     case FAST_ELEMENTS:
       return to_kind == FAST_HOLEY_ELEMENTS;
     case FAST_HOLEY_ELEMENTS:
       return false;
     default:
       return false;
   }
 }
 
 
+ElementsKind GetUnifiedFastElementsKind(ElementsKind kind1,
+                                        ElementsKind kind2) {
+  ASSERT(IsFastElementsKind(kind1));
+  ASSERT(IsFastElementsKind(kind2));
+  if (kind1 == kind2) {
+    return kind1;
+  }
+
+  int i1 = GetSequenceIndexFromFastElementsKind(kind1);
+  int i2 = GetSequenceIndexFromFastElementsKind(kind2);
+  ASSERT(i1 != i2);
+  ElementsKind result = GetFastElementsKindFromSequenceIndex(
+      i1 > i2 ? i1 : i2);
+  return (IsFastHoleyElementsKind(kind1) != IsFastHoleyElementsKind(kind2))
+      ? GetHoleyElementsKind(result)
+      : result;
+}
+
+
 } }  // namespace v8::internal