Reland of Fix FlatTreeTraversal for a slot in a document tree

Reland of Fix FlatTreeTraversal for a slot in a document tree (patchset #1 id:1 of https://codereview.chromium.org/2420883002/ )

Reason for revert:
It looks that the original CL is not culprit because the tests still fail after reverting the CL
  https://build.chromium.org/p/chromium.android/builders/Marshmallow%20Tablet%20Tester/builds/5892

Let me reland this CL.

Original issue's description:
> Revert of Fix FlatTreeTraversal for a slot in a document tree (patchset #3 id:40001 of https://codereview.chromium.org/2416833002/ )
>
> Reason for revert:
> The following content_browsertests have started consistently failing on KitKat Tablet Tester, Lollipop Tablet Tester and Marshmallow Tablet Tester:
>
> FindRequestManagerTests/FindRequestManagerTest.RemoveFrame/0
> FindRequestManagerTest.AddFrameAfterNoMatches
> FindRequestManagerTests/FindRequestManagerTest.AddFrame/0
> FindRequestManagerTest.HiddenFrame
> FindRequestManagerTests/FindRequestManagerTest.CharacterByCharacter/0
> FindRequestManagerTests/FindRequestManagerTest.Basic/0
> FindRequestManagerTest.FindInPage_Issue627799
> FindRequestManagerTest.ActivateNearestFindMatch
> FindRequestManagerTest.FindMatchRects
> FindRequestManagerTests/FindRequestManagerTest.NavigateFrame/0
> FindRequestManagerTest.FindInPage_Issue644448
> FindRequestManagerTests/FindRequestManagerTest.FindNewMatches/0
> FindRequestManagerTests/FindRequestManagerTest.RapidFire/0
>
> e.g. https://build.chromium.org/p/chromium.android/builders/Marshmallow%20Tablet%20Tester/builds/5889
>
> And the stack_tool_with_logcat_dump/stack_tool_for_tombstones steps both prominently feature findPlainTextInternal<blink::EditingAlgorithm<blink::FlatTreeTraversal>>
>
> (oddly on KitKat Tablet Tester these tests started failing on the build after this patch landed; presumably the failure is at least partly flaky)
>
> Original issue's description:
> > Fix FlatTreeTraversal for a slot in a document tree
> >
> > Fix FlatTreeTraversal so that it considers a slot in a document tree correctly.
> >
> > Slots in a document tree are not well supported. They need a special treatment.
> > This CL fixes the crash reported in the bug.
> >
> > BUG=649576
> >
> > Committed: https://crrev.com/dce2e40e8f3b783ef18e06b72c955bf59ed122d9
> > Cr-Commit-Position: refs/heads/master@{#425252}
>
> TBR=tkent@chromium.org,yosin@chromium.org,hayato@chromium.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=649576
>
> Committed: https://crrev.com/3733b9b59c42ea60a6faf1bcfcf0ef30124e90cc
> Cr-Commit-Position: refs/heads/master@{#425293}

TBR=tkent@chromium.org,yosin@chromium.org,johnme@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=649576
Committed: https://crrev.com/cc87e9a3cc8289a23ec23e116196f19c15a9fb49
Cr-Commit-Position: refs/heads/master@{#425621}

[hayato, 2016-10-17 04:22:32]

The CQ bit was checked by hayato@chromium.org

[hayato, 2016-10-17 04:22:32]

Created Reland of Fix FlatTreeTraversal for a slot in a document tree

[commit-bot: I haz the power, 2016-10-17 04:22:46]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[tkent, 2016-10-17 04:35:34]

lgtm

[commit-bot: I haz the power, 2016-10-17 05:48:17]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-10-17 05:49:38]

Description was changed from

==========
Reland of Fix FlatTreeTraversal for a slot in a document tree (patchset #1 id:1
of https://codereview.chromium.org/2420883002/ )

Reason for revert:
It looks that the original CL is not culprit because the tests still fail after
reverting the CL
 
https://build.chromium.org/p/chromium.android/builders/Marshmallow%20Tablet%2...

Let me reland this CL.

Original issue's description:
> Revert of Fix FlatTreeTraversal for a slot in a document tree (patchset #3
id:40001 of https://codereview.chromium.org/2416833002/ )
> 
> Reason for revert:
> The following content_browsertests have started consistently failing on KitKat
Tablet Tester, Lollipop Tablet Tester and Marshmallow Tablet Tester:
> 
> FindRequestManagerTests/FindRequestManagerTest.RemoveFrame/0
> FindRequestManagerTest.AddFrameAfterNoMatches
> FindRequestManagerTests/FindRequestManagerTest.AddFrame/0
> FindRequestManagerTest.HiddenFrame
> FindRequestManagerTests/FindRequestManagerTest.CharacterByCharacter/0
> FindRequestManagerTests/FindRequestManagerTest.Basic/0
> FindRequestManagerTest.FindInPage_Issue627799
> FindRequestManagerTest.ActivateNearestFindMatch
> FindRequestManagerTest.FindMatchRects
> FindRequestManagerTests/FindRequestManagerTest.NavigateFrame/0
> FindRequestManagerTest.FindInPage_Issue644448
> FindRequestManagerTests/FindRequestManagerTest.FindNewMatches/0
> FindRequestManagerTests/FindRequestManagerTest.RapidFire/0
> 
> e.g.
https://build.chromium.org/p/chromium.android/builders/Marshmallow%20Tablet%2...
> 
> And the stack_tool_with_logcat_dump/stack_tool_for_tombstones steps both
prominently feature
findPlainTextInternal<blink::EditingAlgorithm<blink::FlatTreeTraversal>>
> 
> (oddly on KitKat Tablet Tester these tests started failing on the build after
this patch landed; presumably the failure is at least partly flaky)
> 
> Original issue's description:
> > Fix FlatTreeTraversal for a slot in a document tree
> >
> > Fix FlatTreeTraversal so that it considers a slot in a document tree
correctly.
> >
> > Slots in a document tree are not well supported. They need a special
treatment.
> > This CL fixes the crash reported in the bug.
> >
> > BUG=649576
> >
> > Committed: https://crrev.com/dce2e40e8f3b783ef18e06b72c955bf59ed122d9
> > Cr-Commit-Position: refs/heads/master@{#425252}
> 
> TBR=tkent@chromium.org,yosin@chromium.org,hayato@chromium.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=649576
> 
> Committed: https://crrev.com/3733b9b59c42ea60a6faf1bcfcf0ef30124e90cc
> Cr-Commit-Position: refs/heads/master@{#425293}

TBR=tkent@chromium.org,yosin@chromium.org,johnme@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=649576
==========

to

==========
Reland of Fix FlatTreeTraversal for a slot in a document tree (patchset #1 id:1
of https://codereview.chromium.org/2420883002/ )

Reason for revert:
It looks that the original CL is not culprit because the tests still fail after
reverting the CL
 
https://build.chromium.org/p/chromium.android/builders/Marshmallow%20Tablet%2...

Let me reland this CL.

Original issue's description:
> Revert of Fix FlatTreeTraversal for a slot in a document tree (patchset #3
id:40001 of https://codereview.chromium.org/2416833002/ )
>
> Reason for revert:
> The following content_browsertests have started consistently failing on KitKat
Tablet Tester, Lollipop Tablet Tester and Marshmallow Tablet Tester:
>
> FindRequestManagerTests/FindRequestManagerTest.RemoveFrame/0
> FindRequestManagerTest.AddFrameAfterNoMatches
> FindRequestManagerTests/FindRequestManagerTest.AddFrame/0
> FindRequestManagerTest.HiddenFrame
> FindRequestManagerTests/FindRequestManagerTest.CharacterByCharacter/0
> FindRequestManagerTests/FindRequestManagerTest.Basic/0
> FindRequestManagerTest.FindInPage_Issue627799
> FindRequestManagerTest.ActivateNearestFindMatch
> FindRequestManagerTest.FindMatchRects
> FindRequestManagerTests/FindRequestManagerTest.NavigateFrame/0
> FindRequestManagerTest.FindInPage_Issue644448
> FindRequestManagerTests/FindRequestManagerTest.FindNewMatches/0
> FindRequestManagerTests/FindRequestManagerTest.RapidFire/0
>
> e.g.
https://build.chromium.org/p/chromium.android/builders/Marshmallow%20Tablet%2...
>
> And the stack_tool_with_logcat_dump/stack_tool_for_tombstones steps both
prominently feature
findPlainTextInternal<blink::EditingAlgorithm<blink::FlatTreeTraversal>>
>
> (oddly on KitKat Tablet Tester these tests started failing on the build after
this patch landed; presumably the failure is at least partly flaky)
>
> Original issue's description:
> > Fix FlatTreeTraversal for a slot in a document tree
> >
> > Fix FlatTreeTraversal so that it considers a slot in a document tree
correctly.
> >
> > Slots in a document tree are not well supported. They need a special
treatment.
> > This CL fixes the crash reported in the bug.
> >
> > BUG=649576
> >
> > Committed: https://crrev.com/dce2e40e8f3b783ef18e06b72c955bf59ed122d9
> > Cr-Commit-Position: refs/heads/master@{#425252}
>
> TBR=tkent@chromium.org,yosin@chromium.org,hayato@chromium.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=649576
>
> Committed: https://crrev.com/3733b9b59c42ea60a6faf1bcfcf0ef30124e90cc
> Cr-Commit-Position: refs/heads/master@{#425293}

TBR=tkent@chromium.org,yosin@chromium.org,johnme@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=649576

Committed: https://crrev.com/cc87e9a3cc8289a23ec23e116196f19c15a9fb49
Cr-Commit-Position: refs/heads/master@{#425621}
==========

[commit-bot: I haz the power, 2016-10-17 05:49:39]

Patchset 1 (id:??) landed as
https://crrev.com/cc87e9a3cc8289a23ec23e116196f19c15a9fb49
Cr-Commit-Position: refs/heads/master@{#425621}