LoadUint32() doesn't need a scratch register.

src/x64/lithium-x64.cc

Index: src/x64/lithium-x64.cc
diff --git a/src/x64/lithium-x64.cc b/src/x64/lithium-x64.cc
index a3bd9f6b191dbd7b46da2062ccbec0e4f231f559..9bc33833166c4951c1aa32913794cb80b2c689c7 100644
--- a/src/x64/lithium-x64.cc
+++ b/src/x64/lithium-x64.cc
@@ -1904,9 +1904,7 @@ LInstruction* LChunkBuilder::DoChange(HChange* instr) {
     } else {
       ASSERT(to.IsDouble());
       if (val->CheckFlag(HInstruction::kUint32)) {
-        LOperand* temp = FixedTemp(xmm1);
-        return DefineAsRegister(
-            new(zone()) LUint32ToDouble(UseRegister(val), temp));
+        return DefineAsRegister(new(zone()) LUint32ToDouble(UseRegister(val)));
       } else {
         LOperand* value = Use(val);
         return DefineAsRegister(new(zone()) LInteger32ToDouble(value));