createStaticInteropMock<T, U> function Null safety

DO NOT USE - THIS IS UNIMPLEMENTED.

Given a @staticInterop type T and an instance dartMock of a Dart class U that implements the external extension members of T, creates a forwarding mock.

Optionally, you may provide a JS prototype object e.g. the JS value Window.prototype using proto. This allows instanceof and is checks with @Native types to pass with the returned forwarding mock.

When external extension members are called, they will forward to the corresponding implementing member in dartMock. If U does not implement all the external extension members of T, or if U does not properly override them, it will be considered a compile-time error.

For example:

@JS()
@staticInterop
class JSClass {}

extension JSClassExtension on JSClass {
  external String stringify(int param);
}

class DartClass {
  String stringify(num param) => param.toString();
}

...

JSClass mock = createStaticInteropMock<JSClass, DartClass>(DartClass());

TODO(srujzs): Add more detail on how inherited extension members need to be implemented, as well as how conflicts are resolved (if they are resolvable). The semantics here tries to conform to the view type specification.