Fix occurrences for classexpressions

[DickvdBrink]

I looked at some other tests for the getOccurrences and I think I got most of the possibilities.
Tested in highlighting of the occurrences in VS2015.

One small question, the original issue is also talking about find all references on this but that doesn't work in classes either and according to a comment in one of the tests that is currently by design.

The CURRENT behavior is that findAllRefs doesn't work on 'this' or 'super' keywords

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Edit by @DanielRosenwasser: This fixes #4479.

[DanielRosenwasser]

Thanks @DickvdBrink!

[DanielRosenwasser]

Actually, before I pull this in:

One small question, the original issue is also talking about find all references on this but that doesn't work in classes either and according to a comment in one of the tests that is currently by design.

Which test are you talking about? I'm pretty sure I added support for getOccurrences for this everywhere (though findAllRefs doesn't seem to work on this keywords right now).

[DickvdBrink]

Oops, sorry about not providing the link. I really thought I did add it to my post above but I think I didn't press save 👊
The test I was talking about:
https://github.com/Microsoft/TypeScript/blob/59782a98eb36425f4365d423ba11e3bf848066a1/tests/cases/fourslash/findAllRefsThisKeywordMultipleFiles.ts#L18

So yeah, occurrences work but find all refs doesn't, didn't think it mattered though but because issue 4479 was mentioning it I thought I should at least mention it here

[DanielRosenwasser]

@DickvdBrink if you'd like to take that on I think we'd be interested in a PR. If it at least could find this in a function or class, I think that would be pretty helpful.