add &Root<T> checker
Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data:
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- [X] These changes fix#11137 (github issue number if applicable).
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add tidy test for space after ":" in stucts
Addresses issue #10702
the tidy self-test doesn't seem to catch the `member_name:"Foo"` line like it should. the regex follows similar pattern in the file and works in my regex tester tool, so not really sure what is going on there.
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tidy check for vim and emacs modelines
See #10719.
It skips *.webidl files for now since I am not sure where they come from and if they should be edited in tree or not.
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This is a new attempt of #10586, after Simon Sapin's great cleanups in #10749 has landed. I have adjusted the changes to the new structure that was introduced, and also only done a few of the longhand ones. Will certainly continue on this as soon as we have a basic agreement that this style is reasonable.
