Introduce PushQuad and PopQuad for x64 port.

src/x64/macro-assembler-x64.h

Index: src/x64/macro-assembler-x64.h
diff --git a/src/x64/macro-assembler-x64.h b/src/x64/macro-assembler-x64.h
index 4a2fa8e887beffd476e8c36c90c96a340ee8a76d..8719dd6fd0178080dea3d8802edf00c0581c2cc6 100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -844,10 +844,12 @@ class MacroAssembler: public Assembler {
   void Call(Label* target) { call(target); }
   void Push(Register src);
   void Push(const Operand& src);
+  void PushQuad(const Operand& src);
   void Push(Immediate value);
   void PushImm32(int32_t imm32);
   void Pop(Register dst);
   void Pop(const Operand& dst);
+  void PopQuad(const Operand& dst);
   void PushReturnAddressFrom(Register src) { pushq(src); }
   void PopReturnAddressTo(Register dst) { popq(dst); }
   void Move(Register dst, ExternalReference ext) {