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 07803b219c17e4e89fefcc7830ba78e75e915b2e..d6759bf6e35feb06dba5700f16bcc67bde66c0dc 100644
--- a/src/runtime/runtime.h
+++ b/src/runtime/runtime.h
@@ -1111,6 +1111,12 @@ 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,