add context save for GenerateFastApiCall

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index 5410334df57a25862861a81b386e2eafd9409244..e7094686b83abe0c5138b93c8c5c820cc4ef49db 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -2352,7 +2352,7 @@ class FunctionCallbackInfo {
   V8_INLINE(Isolate* GetIsolate() const);
   V8_INLINE(ReturnValue<T> GetReturnValue() const);
   // This shouldn't be public, but the arm compiler needs it.
-  static const int kArgsLength = 6;
+  static const int kArgsLength = 7;
 
  protected:
   friend class internal::FunctionCallbackArguments;
@@ -2360,9 +2360,10 @@ class FunctionCallbackInfo {
   static const int kReturnValueIndex = 0;
   static const int kReturnValueDefaultValueIndex = -1;
   static const int kIsolateIndex = -2;
-  static const int kDataIndex = -3;
-  static const int kCalleeIndex = -4;
-  static const int kHolderIndex = -5;
+  static const int kContextSaveIndex = -3;
+  static const int kDataIndex = -4;
+  static const int kCalleeIndex = -5;
+  static const int kHolderIndex = -6;
 
   V8_INLINE(FunctionCallbackInfo(internal::Object** implicit_args,
                    internal::Object** values,