This Pull Request replaces `contains`, `contains_arguments`, `has_direct_super` and `function_contains_super` with visitors. (~1000 removed lines!)
Also, the new visitor implementation caught a bug where we weren't setting the home object of async functions, generators and async generators for methods of classes, which caused a stack overflow on `super` calls, and I think that's pretty cool!
Next is `var_declared_names`, `lexically_declared_names` and friends, which will be on another PR.
This should hopefully improve our compilation times, both from a clean build and from an incremental compilation snapshot.
Next would be the parser, but it imports `Context`, so it'll require a bit more work.
The number of file changes is obviously big, but almost nothing was changed, I just moved everything to another crate and readjusted the imports of the `parser` module. (Though, I did have to change some details, because there were some functions on the ast that returned `ParseError`s, and the tests had to be moved to the parser)
José Julián Espina