[LayoutNG] Unify LayoutNG invalidation logic to |LayoutObjectChildList|

This patch unifies the same logic separated in two places
into one.

Originally, the logic needed for new LayoutObjects in the
tree is put into |InsertedIntoTree()|. However, some logic
are added to |LayoutObjectChildList| too because they are
needed to run regardless of |notify_layout_object|, which
is an optimization when some of existing notifications can
be skipped for in-tree moves.

As it turned out that all LayoutNG logic are needed
regardless of |notify_layout_object|, this patch moves all
of them to |LayoutObjectChildList|.

The |SplitFlow()| case was found in crbug.com/964619.

Bug: 964854
Change-Id: I777b05fa2355e301ceb713b49d83734546e5ecf7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1617055
Commit-Queue: Emil A Eklund <eae@chromium.org>
Reviewed-by: Emil A Eklund <eae@chromium.org>
Cr-Commit-Position: refs/heads/master@{#661378}
4 files changed