[Display Locking]: Unlock active find-in-page match

Activatable-locked subtrees are counted in total find-in-page matches,
but we currently still skip over them for active match navigation
(the specially-highlighted match). This CL makes us unlock/commit
relevant locked elements needed to show the active match (the ancestors
of the nodes in the active match range). This includes sending the
"beforeactivate" event to those elements.

Bug: 882663
Change-Id: I743faf1391ff0157fdca12a1cbba51fd29a680c9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1491069
Commit-Queue: Rakina Zata Amni <rakina@chromium.org>
Reviewed-by: vmpstr <vmpstr@chromium.org>
Reviewed-by: Kent Tamura <tkent@chromium.org>
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Fergal Daly <fergal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#638467}
7 files changed