Merge 3987: Partially revert |NGPaintFragment::LayoutObjectWillBeDestroyed()|

This patch partially reverts r715954 <crrev.com/c/1914580>.
The patch is to turn use-after-free to null-deref crash, but
from the crash logs, it is possible that we mark "destroyed"
too actively.

This patch reverts to the original method, to check a flag
|is_layout_object_destroyed_| as needed.

As |NGFragmentItem| work make progress, we will need to
investigate this more. But given crashes are occuring in M80,
this is safer than trying to fix the marking.

The partial revert was chosen (over the full revert) as
there are more code that depends on the change to
|NGPhysicalFramgent::layout_object_|.

(cherry picked from commit 0c47fdec7186cfb53c12c07fa4d383cdb6bd0b12)

Bug: 1033203
Change-Id: I7cb21cc09f7250ec031b2efc5c904c342a86aaee
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1963593
Reviewed-by: Ian Kilpatrick <[email protected]>
Commit-Queue: Koji Ishii <[email protected]>
Cr-Original-Commit-Position: refs/heads/master@{#724233}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1971186
Reviewed-by: Koji Ishii <[email protected]>
Cr-Commit-Position: refs/branch-heads/3987@{#203}
Cr-Branched-From: c4e8da9871cc266be74481e212f3a5252972509d-refs/heads/master@{#722274}
2 files changed