HStoreKeyed for Smis optimized for x64 + related redundant moves of elements removed

src/x64/lithium-x64.h

Index: src/x64/lithium-x64.h
diff --git a/src/x64/lithium-x64.h b/src/x64/lithium-x64.h
index 7ba1d30af08a7ee4a2da66d2f280d11681b9d619..962000ad43bd2d63464f4bba3ca49da46fb2f0ec 100644
--- a/src/x64/lithium-x64.h
+++ b/src/x64/lithium-x64.h
@@ -2710,6 +2710,9 @@ class LChunkBuilder V8_FINAL BASE_EMBEDDED {
   // An input operand in a register that may be trashed.
   MUST_USE_RESULT LOperand* UseTempRegister(HValue* value);
 
+  // An input operand in a register that may be trashed or a constant operand.
+  MUST_USE_RESULT LOperand* UseTempRegisterOrConstant(HValue* value);
+
   // An input operand in a register or stack slot.
   MUST_USE_RESULT LOperand* Use(HValue* value);
   MUST_USE_RESULT LOperand* UseAtStart(HValue* value);