lib: add brand checks to AbortController and AbortSignal
Web IDL specifies that both attributes and operations of IDL interfaces should throw a TypeError if this does not implement the interface. These brand checks were missing for AbortController and AbortSignal (as noticed here), so I added them.
Unfortunately, this is not straightforward to test. WPT has an IDL test for this, but it's bunched up together with other IDL tests for EventTarget, Event and CustomEvent. Node supports the first two but not the last one, so the test would still fail.