Complete the full codegenerator on x64.

src/x64/macro-assembler-x64.cc

Index: src/x64/macro-assembler-x64.cc
===================================================================
--- src/x64/macro-assembler-x64.cc	(revision 4685)
+++ src/x64/macro-assembler-x64.cc	(working copy)
@@ -747,7 +747,7 @@
 
 void MacroAssembler::SmiSub(Register dst,
                             Register src1,
-                            Operand const& src2,
+                            const Operand& src2,
                             Label* on_not_smi_result) {
   if (on_not_smi_result == NULL) {
     // No overflow checking. Use only when it's known that
@@ -866,6 +866,7 @@
 
 
 void MacroAssembler::SmiAddConstant(const Operand& dst, Smi* constant) {
+  ASSERT(!dst.is(kScratchRegister));
   if (constant->value() != 0) {
     Move(kScratchRegister, constant);
     addq(dst, kScratchRegister);