Bug 1587989 [wpt PR 19634] - Enable Scroll To Text by default, a=testonly

Bug 1587989 [wpt PR 19634] - Enable Scroll To Text by default, a=testonly

Automatic update from web-platform-tests
Enable Scroll To Text by default (#19634)

Enables scroll to text by default for M81. Note we plan to launch via
Finch for M80.

Intent to ship with LGTMs:
https://groups.google.com/a/chromium.org/d/msg/blink-dev/zlLSxQ9BA8Y/t-_3pAiSAwAJ

This patch also updates web platform test expectations:
- scroll-to-text-fragment.html now passes; it just needed an extra rAF
  for the fallback to element anchor behavior.
- scroll-to-text-fragment-security.html has two expected failures, as
  they need to be updated to test cross-origin navigations. I'll make
  this change in a follow-up patch to close bug 1042311.

Bug: 919204
Change-Id: Ic2d563934cd9406fb335904a94c390bba789e0b4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1838701
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Reviewed-by: David Bokan <bokan@chromium.org>
Commit-Queue: Nick Burris <nburris@chromium.org>
Cr-Commit-Position: refs/heads/master@{#732592}

Co-authored-by: Nick Burris <nburris@chromium.org>
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wpt-commits: 91ae81eb86ffffeed3abee0f45ccfcd3f82750ef
wpt-pr: 19634