Respect filters for internal intersection observers

Though the IntersectionObserver V1 spec says not to respect filters,
some internal intersection observers specifically require to respect
filters (e.g.
https://drafts.csswg.org/css-contain-2/#:~:text=If%20a%20filter).

This CL is kept small by reverting crrev.com/c/4960480 for all
internal intersection observers. Ideally we should allow each
internal intersection observer to decide whether to respect filters,
which will be done later.

This CL also removes the IntersectionObserverIgnoreFilters flag, and
make the behavior of js IntersectionObserver ignoring filters
permanent.

Bug: 1494181
Change-Id: I6ace2599b1cf34bc5aed0515b6329882803bbec9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5154059
Reviewed-by: Vladimir Levin <vmpstr@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1241533}