Expose JSON stringifier through V8 API

src/runtime/runtime.h

Index: src/runtime/runtime.h
diff --git a/src/runtime/runtime.h b/src/runtime/runtime.h
index 25a60fdd27fe5751c6014b17196f0479febdbf4a..fd21bcb19a4d1bf436c547f2aafe973f325a5b4b 100644
--- a/src/runtime/runtime.h
+++ b/src/runtime/runtime.h
@@ -1110,6 +1110,12 @@ class Runtime : public AllStatic {
   MUST_USE_RESULT static MaybeHandle<Object> GetObjectProperty(
       Isolate* isolate, Handle<Object> object, Handle<Object> key);
 
+  MUST_USE_RESULT static MaybeHandle<Object> BasicJsonStringify(
+      Isolate* isolate, Handle<Object> object);
+
+  MUST_USE_RESULT static MaybeHandle<Object> BasicJsonStringifyString(
+      Isolate* isolate, Handle<String> string);
+
   enum TypedArrayId {
     // arrayIds below should be synchronized with typedarray.js natives.
     ARRAY_ID_UINT8 = 1,