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 e644c2d25acfe9456a68e4039abd4ac358568369..4b91d1d7f3aaa001dec47909d611963ee08cf78d 100644
--- a/src/x64/lithium-x64.h
+++ b/src/x64/lithium-x64.h
@@ -2714,6 +2714,9 @@ 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);