Don't stop text-decoration propagation at non-UA shadow boundaries.

There is no spec saying this should happen. Neither Gecko nor WebKit
does this, and it breaks devtools UX. We still need to stop propagation
into UA shadow trees to avoid text-decoration applying to media
controls, for instance.

Bug: 938193
Change-Id: I21895cb36b0d0bf2b39b42c000d3cf5ceb4255f1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1508097
Reviewed-by: Anders Hartvoll Ruud <andruud@chromium.org>
Reviewed-by: Hayato Ito <hayato@chromium.org>
Commit-Queue: Rune Lillesveen <futhark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#638571}
5 files changed