Phase 3: Attach comments

[nzakas]

Phase 3 is to add attaching leading/trailing comments to the AST inside the parser. This would involve:

1. Retrieving comments for each node.
2. Converting the TypeScript comments into Esprima-style comments.
3. Adding the comments into leadingComments and trailingComments arrays on appropriate nodes.
4. Making the result pass the tests that are already tests in tests/fixtures/attach-comments.

[nzakas]

astexplorer.net seems able to get leading and trailing comments for TypeScript, so it seems like there's probably already an API somewhere for getting that information. It might be worth looking at the astexplorer.net source for hints.

[JamesHenry]

As mentioned on gitter, I have made some decent progress on this. 9 test cases to go!