Revert "Don't need a temp register for StoreKeyed double"

This reverts commit r19829 for breaking the mozilla tests.

R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/196343003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19830 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/x64/lithium-x64.cc

@@ -2114,7 +2114,7 @@ LInstruction* LChunkBuilder::DoStoreKeyed(HStoreKeyed* instr) {
     Representation value_representation = instr->value()->representation();
     if (value_representation.IsDouble()) {
       object = UseRegisterAtStart(instr->elements());
-      val = UseRegisterAtStart(instr->value());
+      val = UseTempRegister(instr->value());
       key = UseRegisterOrConstantAtStart(instr->key());
     } else {
       ASSERT(value_representation.IsSmiOrTagged() ||