Don't explicitly pass requested representations to constants; implement ConstantS

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index 74834a08c30e9f1b29ab192c535ff489accfabca..d8f73c0fec36b2f5db88d3616acf9b37a0bb2a1a 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -1565,6 +1565,12 @@ void LCodeGen::DoConstantI(LConstantI* instr) {
 }
 
 
+void LCodeGen::DoConstantS(LConstantS* instr) {
+  ASSERT(instr->result()->IsRegister());
+  __ Move(ToRegister(instr->result()), instr->value());
+}
+
+
 void LCodeGen::DoConstantD(LConstantD* instr) {
   ASSERT(instr->result()->IsDoubleRegister());
   XMMRegister res = ToDoubleRegister(instr->result());