Skip canonicalization check in LStoreKeyedFastDoubleElement when it is not needed:

src/hydrogen-instructions.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 4192 matching lines @@
   }
 
   HValue* elements() { return OperandAt(0); }
   HValue* key() { return OperandAt(1); }
   HValue* value() { return OperandAt(2); }
 
   bool NeedsWriteBarrier() {
     return StoringValueNeedsWriteBarrier(value());
   }
 
+  bool NeedsCanonicalization();
+
   virtual void PrintDataTo(StringStream* stream);
 
   DECLARE_CONCRETE_INSTRUCTION(StoreKeyedFastDoubleElement)
 };
 
 
 class HStoreKeyedSpecializedArrayElement: public HTemplateInstruction<3> {
  public:
   HStoreKeyedSpecializedArrayElement(HValue* external_elements,
                                      HValue* key,
@@ skipping 678 matching lines @@
   DECLARE_CONCRETE_INSTRUCTION(LoadFieldByIndex);
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_