Fix LGapResolver::EmitMove for X64 when the dst is a double register and src is a constant

src/x64/lithium-gap-resolver-x64.cc

Index: src/x64/lithium-gap-resolver-x64.cc
===================================================================
--- src/x64/lithium-gap-resolver-x64.cc	(revision 15613)
+++ src/x64/lithium-gap-resolver-x64.cc	(working copy)
@@ -205,16 +205,12 @@
     } else if (destination->IsDoubleRegister()) {
       double v = cgen_->ToDouble(constant_source);
       uint64_t int_val = BitCast<uint64_t, double>(v);
-      int32_t lower = static_cast<int32_t>(int_val);
-      int32_t upper = static_cast<int32_t>(int_val >> (kBitsPerInt));
       XMMRegister dst = cgen_->ToDoubleRegister(destination);
       if (int_val == 0) {
         __ xorps(dst, dst);
       } else {
-        __ push(Immediate(upper));
-        __ push(Immediate(lower));
-        __ movsd(dst, Operand(rsp, 0));
-        __ addq(rsp, Immediate(kDoubleSize));
+        __ movq(kScratchRegister, int_val, RelocInfo::NONE64);
+        __ movq(dst, kScratchRegister);
       }
     } else {
       ASSERT(destination->IsStackSlot());