add context save for GenerateFastApiCall

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 8e30981833acff2e6caac0b8ddf2b0276d51c9de..4c89abaa055a40c463fcdef4b137bb5cde91b7f2 100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -302,7 +302,7 @@ class MacroAssembler: public Assembler {
 
   // Leave the current exit frame. Expects/provides the return value in
   // register rax (untouched).
-  void LeaveApiExitFrame();
+  void LeaveApiExitFrame(bool restore_context);
 
   // Push and pop the registers that can hold pointers.
   void PushSafepointRegisters() { Pushad(); }
@@ -1260,7 +1260,8 @@ class MacroAssembler: public Assembler {
                                 Address thunk_address,
                                 Register thunk_last_arg,
                                 int stack_space,
-                                int return_value_offset_from_rbp);
+                                int return_value_offset_from_rbp,
+                                int restore_context_offset_from_rbp = 0);
 
   // Before calling a C-function from generated code, align arguments on stack.
   // After aligning the frame, arguments must be stored in rsp[0], rsp[8],
@@ -1416,7 +1417,7 @@ class MacroAssembler: public Assembler {
   // accessible via StackSpaceOperand.
   void EnterExitFrameEpilogue(int arg_stack_space, bool save_doubles);
 
-  void LeaveExitFrameEpilogue();
+  void LeaveExitFrameEpilogue(bool restore_context);
 
   // Allocation support helpers.
   // Loads the top of new-space into the result register.