Allow all entrypoints support by the command line VM. (flutter#7717)

lib/ui/hooks.dart

@@ -168,12 +168,26 @@ void _drawFrame() {
   _invoke(window.onDrawFrame, window._onDrawFrameZone);
 }
 
+// ignore: always_declare_return_types, prefer_generic_function_type_aliases
+typedef _UnaryFunction(Null args);
+// ignore: always_declare_return_types, prefer_generic_function_type_aliases
+typedef _BinaryFunction(Null args, Null message);
+
 @pragma('vm:entry-point')
 // ignore: unused_element
 void _runMainZoned(Function startMainIsolateFunction, Function userMainFunction) {
   startMainIsolateFunction((){
     runZoned<Future<void>>(() {
-      userMainFunction();
+      const List<String> empty_args = <String>[];
+      if (userMainFunction is _BinaryFunction) {
+        // This seems to be undocumented but supported by the command line VM.
+        // Let's do the same in case old entry-points are ported to Flutter.
+        (userMainFunction as dynamic)(empty_args, '');
+      } else if (userMainFunction is _UnaryFunction) {
+        (userMainFunction as dynamic)(empty_args);
+      } else {
+        userMainFunction();
+      }
     }, onError: (Object error, StackTrace stackTrace) {
       _reportUnhandledException(error.toString(), stackTrace.toString());
     });