Make find-in-page inert check look at flat tree
This patch didn't look at the flat tree, so it regressed the case where
dialogs are in a shadowroot and the case where text is slotted into a
dialog: http://crrev.com/1270044
Fixed: 336832613
Change-Id: Id592aee16774e92d96e695558365b5715900aab9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5502209
Reviewed-by: Oriol Brufau obrufau@igalia.com
Commit-Queue: Joey Arhar jarhar@chromium.org
Cr-Commit-Position: refs/heads/main@{#1294938}