Add to the doc output: the union of return and parameter types!

[kevmoo]

We return JSObject often. We could document we return a union of more specific types!

[srujzs]

This occurs in parameters as well e.g. set innerHTML where we accept a String and a TrustedHTML but are forced to use JSAny.

We could use annotations of some kind to represent unions for parameters that would then trigger the analyzer, but in the absence of that, documentation would be nice. The annotation approach doesn't really work for return types though.

[kevmoo]

We could just add the doc comment to the member, right?

[srujzs]

Right. Sometimes the MDN documentation that already exists mentions the accepted/returned values, sometimes it doesn't.