[DL]: Check whether we have locked display locks before checking ancestors.

This patch fixes one spot that navigates up the ancestor chain to first
check whether the document has any locked display locks.

R=chrishtr@chromium.org

Bug: 882663
Change-Id: I461d01e339ecd82ff14e3732dfa1cec79c054c9c
Reviewed-on: https://chromium-review.googlesource.com/c/1473812
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Commit-Queue: vmpstr <vmpstr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#632345}
1 file changed