Remove some Emacs & Vim modelines

[edunham]

This might be a bad idea, especially on the webidl side. However, we started talking about the idea that modelines are a lint error (#10719), and these changes would be required before enabling a modeline lint.

If it bitrots, it's easy to recreate with

find * -type f -exec sed '/- Mode:/d' -i {} +
find * -type f -exec sed '/ vim:/d' -i {} +
git checkout -- python/tidy/servo_tidy/tidy.py
git checkout -- python/tidy/servo_tidy_tests/spec.webidl
git commit -a

---

This change is

[highfive]

Heads up! This PR modifies the following files:

• @KiChjang: https://gist.github.com/edunham/5c7e80c57b9ff8803b3008981ef8ac6e
  (edited by edunham because the files modified list was a ridiculous wall of text)

[highfive]

Warning

• This pull request modifies the contents of
  'tests/wpt/css-tests/', which are overwriten occasionally whenever the
  directory is synced from upstream.

[Ms2ger]

Definitely r- on the changes to tests/wpt.

[wafflespeanut]

@bors-servo r+

[bors-servo]

📌 Commit 7ae63b1 has been approved by Wafflespeanut

[bors-servo]

⌛ Testing commit 7ae63b1 with merge dff217c...

[bors-servo]

☀️ Test successful - android, arm32, arm64, linux-dev, linux-rel, mac-dev-unit, mac-rel-css, mac-rel-wpt