ecma_transforms:
- implement es2015::instanceof
- implement es2015::typeof_symbol
- implement inline_globals pass
ecma_parser:
- `PResult<T>` is now `Result<T, ()>` and `Err(())` means that an error is emitted.
- add docs
- Make rls happy.
- Some minor parser error improvements.
- Add reference files for ecmascript parser errors.
- Improve error message of import/export used outside of a module