test(isolate): adjust tests for new isolation semantics
test(isolate): adjust tests for new isolation semantics

- Add test ensuring that a className is added to a vtree that
previously had none
- Add test ensuring isolateSink prevents a parent from selecting
inside of an isolation boundary
- Add test to ensure an isolated component can select() its root

motorcyclejs/motorcyclejs,motorcyclejs/motorcyclejs,motorcyclejs/motorcyclejs