LoadUint32() doesn't need a scratch register.

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 fe7046f1e73a420802c27ea9d8e0c1bf01dd2f20..3f228249f3a2fcc0c2c12a1c3ba5480eb52b14ac 100644
--- a/src/x64/lithium-x64.h
+++ b/src/x64/lithium-x64.h
@@ -1967,15 +1967,13 @@ class LInteger32ToDouble V8_FINAL : public LTemplateInstruction<1, 1, 0> {
 };
 
 
-class LUint32ToDouble V8_FINAL : public LTemplateInstruction<1, 1, 1> {
+class LUint32ToDouble V8_FINAL : public LTemplateInstruction<1, 1, 0> {
  public:
-  explicit LUint32ToDouble(LOperand* value, LOperand* temp) {
+  explicit LUint32ToDouble(LOperand* value) {
     inputs_[0] = value;
-    temps_[0] = temp;
   }
 
   LOperand* value() { return inputs_[0]; }
-  LOperand* temp() { return temps_[0]; }
 
   DECLARE_CONCRETE_INSTRUCTION(Uint32ToDouble, "uint32-to-double")
 };