Don’t enter node::MakeCallback if we have a calling context

this means we already have JavaScript frames on the execution stack

src/node/node_function.hpp

@@ -38,6 +38,14 @@ inline v8::Local<v8::Value> node::Function::call(v8::Isolate* isolate, const v8:
 
 template<>
 inline v8::Local<v8::Value> node::Function::callback(v8::Isolate* isolate, const v8::Local<v8::Function> &function, const v8::Local<v8::Object> &this_object, size_t argc, const v8::Local<v8::Value> arguments[]) {
+    if (!isolate->GetCallingContext().IsEmpty()) {
+        // if there are any JavaScript frames on the stack below this one we don't need to
+        // go through the trouble of calling MakeCallback. MakeCallback is only for when a
+        // thread with no JavaScript frames on its stack needs to call into JavaScript, like in
+        // an uv_async callback.
+        return call(isolate, function, this_object, argc, arguments);
+    }
+
     v8::TryCatch trycatch(isolate);
     
     auto recv = this_object.IsEmpty() ? isolate->GetCurrentContext()->Global() : this_object;