[wpt] Fix form-controls/resets.html table box-sizing.

This test was added in:
https://github.com/web-platform-tests/wpt/pull/20148/commits/36b6813aa59c6dd5c67c28bbb107c941fddd8a74

But tables should have "box-sizing: border-box" in the UA stylesheet.

See: https://html.spec.whatwg.org/#tables-2
Change-Id: I1934c8dabcea90554976ba057f1ddedb04711abd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3380049


Reviewed-by: Mason Freed <masonf@chromium.org>
Commit-Queue: Ian Kilpatrick <ikilpatrick@chromium.org>
Cr-Commit-Position: refs/heads/main@{#958203}