[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks()|

[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks()|

The root cause is we are removing & re-inserting children nodes during
|CompositeEditCommand::removeNodePreservingChildren()|, which means if the child
contains style "* {-webkit-user-modify: read-write;}" we won't be able to re-insert
it back as parent has lost editable attribute as soon as we've removed it.

BUG=675727
Committed: https://crrev.com/3c4ea2111cb111f66c87f8cd6bf3909eeaa15c9b
Cr-Commit-Position: refs/heads/master@{#440459}

[chongz, 2016-12-21 01:45:16]

The CQ bit was checked by chongz@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-12-21 01:46:03]

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

[chongz, 2016-12-21 01:55:04]

Description was changed from

==========
Add null check in DeleteSelectionCommand::removeRedundantBlocks

BUG=675727
==========

to

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks|

|Node::parentNode()| could be null by executing |node.outerHTML = ''|, so we
need
to do null check before proceeding.

BUG=675727
==========

[chongz, 2016-12-21 01:57:25]

Description was changed from

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks|

|Node::parentNode()| could be null by executing |node.outerHTML = ''|, so we
need
to do null check before proceeding.

BUG=675727
==========

to

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks|

|Node::parentNode()| could be null by executing |node.outerHTML = ''|, so we
need
to do null check before proceeding.

However it's hard to minimize a test case as the one from clusterfuzz is too
complex.

BUG=675727
==========

[chongz, 2016-12-21 01:58:26]

Description was changed from

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks|

|Node::parentNode()| could be null by executing |node.outerHTML = ''|, so we
need
to do null check before proceeding.

However it's hard to minimize a test case as the one from clusterfuzz is too
complex.

BUG=675727
==========

to

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks|

|Node::parentNode()| could be null by executing |node.outerHTML = ''|, so we
need
to do null check before proceeding.

However it's hard to minimize a test case as the one from clusterfuzz is too
complex.

TEST=https://cluster-fuzz.appspot.com/download/AMIfv94ZvHhjFEVY0tUnt5jhZc6Vj-WRFIMwOlUl-jbFJvxsU97o-VP74cJ4NwaReSV4PBIEE8qZ1q-eGkMGeu3KXCsvHiSiyoIINmpwzPoU6PWiWgqxIY93jkdXQ60TrfwB_pT9xbMtWWmTSTtTLA1Up2mdZotImw?testcase_id=4800242794102784

BUG=675727
==========

[chongz, 2016-12-21 01:58:39]

Description was changed from

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks|

|Node::parentNode()| could be null by executing |node.outerHTML = ''|, so we
need
to do null check before proceeding.

However it's hard to minimize a test case as the one from clusterfuzz is too
complex.

TEST=https://cluster-fuzz.appspot.com/download/AMIfv94ZvHhjFEVY0tUnt5jhZc6Vj-WRFIMwOlUl-jbFJvxsU97o-VP74cJ4NwaReSV4PBIEE8qZ1q-eGkMGeu3KXCsvHiSiyoIINmpwzPoU6PWiWgqxIY93jkdXQ60TrfwB_pT9xbMtWWmTSTtTLA1Up2mdZotImw?testcase_id=4800242794102784

BUG=675727
==========

to

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks|

|Node::parentNode()| could be null by executing |node.outerHTML = ''|, so we
need
to do null check before proceeding.

However it's hard to minimize a test case as the one from clusterfuzz is too
complex.

TEST:
https://cluster-fuzz.appspot.com/download/AMIfv94ZvHhjFEVY0tUnt5jhZc6Vj-WRFIM...

BUG=675727
==========

[chongz, 2016-12-21 01:59:27]

Description was changed from

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks|

|Node::parentNode()| could be null by executing |node.outerHTML = ''|, so we
need
to do null check before proceeding.

However it's hard to minimize a test case as the one from clusterfuzz is too
complex.

TEST:
https://cluster-fuzz.appspot.com/download/AMIfv94ZvHhjFEVY0tUnt5jhZc6Vj-WRFIM...

BUG=675727
==========

to

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks|

|Node::parentNode()| could be null by executing |node.outerHTML = ''|, so we
need
to do null check before proceeding.

However it's hard to minimize a test case as the one from clusterfuzz is too
complex.

Minimized Testcase from ClusterFuzz:
https://cluster-fuzz.appspot.com/download/AMIfv94ZvHhjFEVY0tUnt5jhZc6Vj-WRFIM...

BUG=675727
==========

[chongz, 2016-12-21 02:01:00]

Description was changed from

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks|

|Node::parentNode()| could be null by executing |node.outerHTML = ''|, so we
need
to do null check before proceeding.

However it's hard to minimize a test case as the one from clusterfuzz is too
complex.

Minimized Testcase from ClusterFuzz:
https://cluster-fuzz.appspot.com/download/AMIfv94ZvHhjFEVY0tUnt5jhZc6Vj-WRFIM...

BUG=675727
==========

to

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks|

|Node::parentNode()| could be null by executing |node.outerHTML = ''|, so we
need
to do null check before proceeding.

However it's hard to minimize a test case as the one from clusterfuzz is too
complex.

Note:
Safari has this issue as well.

Minimized Testcase from ClusterFuzz:
https://cluster-fuzz.appspot.com/download/AMIfv94ZvHhjFEVY0tUnt5jhZc6Vj-WRFIM...

BUG=675727
==========

[chongz, 2016-12-21 02:01:54]

Description was changed from

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks|

|Node::parentNode()| could be null by executing |node.outerHTML = ''|, so we
need
to do null check before proceeding.

However it's hard to minimize a test case as the one from clusterfuzz is too
complex.

Note:
Safari has this issue as well.

Minimized Testcase from ClusterFuzz:
https://cluster-fuzz.appspot.com/download/AMIfv94ZvHhjFEVY0tUnt5jhZc6Vj-WRFIM...

BUG=675727
==========

to

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks|

|Node::parentNode()| could be null by executing |node.outerHTML = ''|, so we
need
to do null check before proceeding.

Note:
Safari has this issue as well.

Minimized Testcase from ClusterFuzz:
https://cluster-fuzz.appspot.com/download/AMIfv94ZvHhjFEVY0tUnt5jhZc6Vj-WRFIM...

BUG=675727
==========

[chongz, 2016-12-21 02:03:44]

chongz@chromium.org changed reviewers:
+ xiaochengh@chromium.org

[chongz, 2016-12-21 02:03:45]

xiaochengh@ PTAL, thanks!

[Xiaocheng, 2016-12-21 02:47:41]

Please add a regression test. A unit test is preferred.

The clusterfuzz-minimized test case is not very readable. A good regression test
helps us understand the root cause.

[commit-bot: I haz the power, 2016-12-21 03:19:37]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-12-21 03:19:38]

Dry run: This issue passed the CQ dry run.

[chongz, 2016-12-21 17:39:32]

The CQ bit was checked by chongz@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-12-21 17:39:59]

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

[chongz, 2016-12-21 17:43:56]

Description was changed from

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks|

|Node::parentNode()| could be null by executing |node.outerHTML = ''|, so we
need
to do null check before proceeding.

Note:
Safari has this issue as well.

Minimized Testcase from ClusterFuzz:
https://cluster-fuzz.appspot.com/download/AMIfv94ZvHhjFEVY0tUnt5jhZc6Vj-WRFIM...

BUG=675727
==========

to

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks|

The root cause is we are removing & re-inserting children nodes during
|DeleteSelectionCommand::removeRedundantBlocks()|, which means if the child
contains style "* {-webkit-user-modify: read-write;}" we won't be able to
re-insert
it back as parent has lost editable attribute after removing it.

Note:
Safari has this issue as well.

Minimized Testcase from ClusterFuzz:
https://cluster-fuzz.appspot.com/download/AMIfv94ZvHhjFEVY0tUnt5jhZc6Vj-WRFIM...

BUG=675727
==========

[chongz, 2016-12-21 17:44:46]

Description was changed from

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks|

The root cause is we are removing & re-inserting children nodes during
|DeleteSelectionCommand::removeRedundantBlocks()|, which means if the child
contains style "* {-webkit-user-modify: read-write;}" we won't be able to
re-insert
it back as parent has lost editable attribute after removing it.

Note:
Safari has this issue as well.

Minimized Testcase from ClusterFuzz:
https://cluster-fuzz.appspot.com/download/AMIfv94ZvHhjFEVY0tUnt5jhZc6Vj-WRFIM...

BUG=675727
==========

to

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks()|

The root cause is we are removing & re-inserting children nodes during
|CompositeEditCommand::removeNodePreservingChildren()|, which means if the child
contains style "* {-webkit-user-modify: read-write;}" we won't be able to
re-insert
it back as parent has lost editable attribute after removing it.

Note:
Safari has this issue as well.

Minimized Testcase from ClusterFuzz:
https://cluster-fuzz.appspot.com/download/AMIfv94ZvHhjFEVY0tUnt5jhZc6Vj-WRFIM...

BUG=675727
==========

[chongz, 2016-12-21 17:45:22]

Description was changed from

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks()|

The root cause is we are removing & re-inserting children nodes during
|CompositeEditCommand::removeNodePreservingChildren()|, which means if the child
contains style "* {-webkit-user-modify: read-write;}" we won't be able to
re-insert
it back as parent has lost editable attribute after removing it.

Note:
Safari has this issue as well.

Minimized Testcase from ClusterFuzz:
https://cluster-fuzz.appspot.com/download/AMIfv94ZvHhjFEVY0tUnt5jhZc6Vj-WRFIM...

BUG=675727
==========

to

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks()|

The root cause is we are removing & re-inserting children nodes during
|CompositeEditCommand::removeNodePreservingChildren()|, which means if the child
contains style "* {-webkit-user-modify: read-write;}" we won't be able to
re-insert
it back as parent has lost editable attribute as soon as we've removed it.

Note:
Safari has this issue as well.

Minimized Testcase from ClusterFuzz:
https://cluster-fuzz.appspot.com/download/AMIfv94ZvHhjFEVY0tUnt5jhZc6Vj-WRFIM...

BUG=675727
==========

[commit-bot: I haz the power, 2016-12-21 18:20:40]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-12-21 18:20:41]

Dry run: Try jobs failed on following builders:
  linux_chromium_compile_dbg_ng on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[chongz, 2016-12-21 23:45:27]

The CQ bit was checked by chongz@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-12-21 23:45:43]

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

[chongz, 2016-12-21 23:59:53]

Patchset #2 (id:20001) has been deleted

[chongz, 2016-12-22 00:06:43]

xiaochengh@ I've added a simpler layout test and updated CL description, does
that look good to you?

I tried to minimized it into a unit test but failed as I'm not very familiar
about the details of |DeleteSelectionCommand| and |ApplyStyleCommand|.

[commit-bot: I haz the power, 2016-12-22 01:28:25]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-12-22 01:28:26]

Dry run: This issue passed the CQ dry run.

[Xiaocheng, 2016-12-22 03:25:51]

xiaochengh@chromium.org changed reviewers:
+ dominicc@chromium.org

[Xiaocheng, 2016-12-22 03:25:52]

I agree that it's a little bit tricky to make it a unit test, so lgtm with code
change.

+dominicc

https://codereview.chromium.org/2595783002/diff/40001/third_party/WebKit/Layo...
File
third_party/WebKit/LayoutTests/editing/execCommand/justify-center-editable-style-on-child-crash.html
(right):

https://codereview.chromium.org/2595783002/diff/40001/third_party/WebKit/Layo...
third_party/WebKit/LayoutTests/editing/execCommand/justify-center-editable-style-on-child-crash.html:1:
<title>Justify center and remove redounded div wont crash</title>
Could you mentioned the bug number in the layout test?

[Xiaocheng, 2016-12-22 03:27:18]

On 2016/12/22 at 03:25:52, Xiaocheng wrote:
> I agree that it's a little bit tricky to make it a unit test, so lgtm with
code change.
> 
> +dominicc
> 
>
https://codereview.chromium.org/2595783002/diff/40001/third_party/WebKit/Layo...
> File
third_party/WebKit/LayoutTests/editing/execCommand/justify-center-editable-style-on-child-crash.html
(right):
> 
>
https://codereview.chromium.org/2595783002/diff/40001/third_party/WebKit/Layo...
>
third_party/WebKit/LayoutTests/editing/execCommand/justify-center-editable-style-on-child-crash.html:1:
<title>Justify center and remove redounded div wont crash</title>
> Could you mentioned the bug number in the layout test?

ClusterFuzz is not accessible by everyone. Could you also remove the link from
patch description?

[chongz, 2016-12-22 03:52:10]

Description was changed from

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks()|

The root cause is we are removing & re-inserting children nodes during
|CompositeEditCommand::removeNodePreservingChildren()|, which means if the child
contains style "* {-webkit-user-modify: read-write;}" we won't be able to
re-insert
it back as parent has lost editable attribute as soon as we've removed it.

Note:
Safari has this issue as well.

Minimized Testcase from ClusterFuzz:
https://cluster-fuzz.appspot.com/download/AMIfv94ZvHhjFEVY0tUnt5jhZc6Vj-WRFIM...

BUG=675727
==========

to

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks()|

The root cause is we are removing & re-inserting children nodes during
|CompositeEditCommand::removeNodePreservingChildren()|, which means if the child
contains style "* {-webkit-user-modify: read-write;}" we won't be able to
re-insert
it back as parent has lost editable attribute as soon as we've removed it.

Note:
Safari has this issue as well.

BUG=675727
==========

[dominicc (has gone to gerrit), 2016-12-22 03:56:33]

Your change description is really clear, very nice.

I don't think you need to mention Safari since this isn't really interesting
from a web compatibility perspective. Maybe just comment on the CR bug and
include something useful like the Safari version number?

+1 to all of xiaochengh's comments.

Some more comments of my own inline to improve the test.

You mentioned unit testing in was hard; can you upload a WIP patch of what you
tried? What in particular was hard?

https://codereview.chromium.org/2595783002/diff/40001/third_party/WebKit/Layo...
File
third_party/WebKit/LayoutTests/editing/execCommand/justify-center-editable-style-on-child-crash.html
(right):

https://codereview.chromium.org/2595783002/diff/40001/third_party/WebKit/Layo...
third_party/WebKit/LayoutTests/editing/execCommand/justify-center-editable-style-on-child-crash.html:15:
const li = document.getElementsByTagName("li")[0];
If you just do querySelector you'll get the 0th one.

https://codereview.chromium.org/2595783002/diff/40001/third_party/WebKit/Layo...
third_party/WebKit/LayoutTests/editing/execCommand/justify-center-editable-style-on-child-crash.html:18:
}, 'Justify center and remove redounded div wont crash');
This description needs some work. Is this Justify, center and remove something?
If it's a sequence a comma makes it easier to understand that.

What is redounded?

wont => won't

[chongz, 2016-12-22 03:57:12]

The CQ bit was checked by chongz@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-12-22 03:57:27]

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

[chongz, 2016-12-22 04:00:13]

Description was changed from

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks()|

The root cause is we are removing & re-inserting children nodes during
|CompositeEditCommand::removeNodePreservingChildren()|, which means if the child
contains style "* {-webkit-user-modify: read-write;}" we won't be able to
re-insert
it back as parent has lost editable attribute as soon as we've removed it.

Note:
Safari has this issue as well.

BUG=675727
==========

to

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks()|

The root cause is we are removing & re-inserting children nodes during
|CompositeEditCommand::removeNodePreservingChildren()|, which means if the child
contains style "* {-webkit-user-modify: read-write;}" we won't be able to
re-insert
it back as parent has lost editable attribute as soon as we've removed it.

BUG=675727
==========

[chongz, 2016-12-22 04:27:06]

The CQ bit was checked by chongz@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-12-22 04:27:13]

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

[chongz, 2016-12-22 04:27:58]

The CQ bit was checked by chongz@chromium.org to run a CQ dry run

[chongz, 2016-12-22 04:28:04]

Patchset #3 (id:60001) has been deleted

[commit-bot: I haz the power, 2016-12-22 04:28:13]

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

[chongz, 2016-12-22 04:30:34]

Patchset #3 (id:80001) has been deleted

[chongz, 2016-12-22 04:30:42]

The CQ bit was checked by chongz@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-12-22 04:30:55]

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

[chongz, 2016-12-22 05:14:50]

dominicc@ Thanks for the review!
I've:
1. Added bug number to layout test;
2. Removed ClusterFuzz link;
3. Removed note about Safari;
4. Upload WIP patch for unit tests https://crrev.com/2599663002
5. Switched to using |querySelector()|
6. Updated description in layout tests

PTAL again, thanks!

https://codereview.chromium.org/2595783002/diff/40001/third_party/WebKit/Layo...
File
third_party/WebKit/LayoutTests/editing/execCommand/justify-center-editable-style-on-child-crash.html
(right):

https://codereview.chromium.org/2595783002/diff/40001/third_party/WebKit/Layo...
third_party/WebKit/LayoutTests/editing/execCommand/justify-center-editable-style-on-child-crash.html:1:
<title>Justify center and remove redounded div wont crash</title>
On 2016/12/22 03:25:51, Xiaocheng wrote:
> Could you mentioned the bug number in the layout test?

Done.

https://codereview.chromium.org/2595783002/diff/40001/third_party/WebKit/Layo...
third_party/WebKit/LayoutTests/editing/execCommand/justify-center-editable-style-on-child-crash.html:15:
const li = document.getElementsByTagName("li")[0];
On 2016/12/22 03:56:32, dominicc (away 12.23-1.10) wrote:
> If you just do querySelector you'll get the 0th one.

Done.

https://codereview.chromium.org/2595783002/diff/40001/third_party/WebKit/Layo...
third_party/WebKit/LayoutTests/editing/execCommand/justify-center-editable-style-on-child-crash.html:18:
}, 'Justify center and remove redounded div wont crash');
On 2016/12/22 03:56:32, dominicc (away 12.23-1.10) wrote:
> This description needs some work. Is this Justify, center and remove
something?
> If it's a sequence a comma makes it easier to understand that.
> 
> What is redounded?
> 
> wont => won't

Sorry for the typo... I've added a comment for the redundant <div> and moved
description to <title> (Since there is only one test case).

[commit-bot: I haz the power, 2016-12-22 06:13:37]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-12-22 06:13:37]

Dry run: This issue passed the CQ dry run.

[dominicc (has gone to gerrit), 2016-12-22 12:11:06]

lgtm

LGTM, thank you.

Use your judgement about including the unit test. I think you should include it
but I could be persuaded either way.

You can ignore my comment about the DOM in that unit test; Xiaocheng explained
it's simply hand minimized and hand minimization would go no further. That's
fine if there's no deeper theory about what's happening in this bug.

[chongz, 2016-12-22 16:40:55]

The CQ bit was checked by chongz@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-12-22 16:41:13]

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

[commit-bot: I haz the power, 2016-12-22 18:28:55]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-12-22 18:28:56]

Dry run: This issue passed the CQ dry run.

[chongz, 2016-12-22 18:49:34]

On 2016/12/22 12:11:06, dominicc (away 12.23-1.10) wrote:
> lgtm
> 
> LGTM, thank you.
> 
> Use your judgement about including the unit test. I think you should include
it
> but I could be persuaded either way.
> 
> You can ignore my comment about the DOM in that unit test; Xiaocheng explained
> it's simply hand minimized and hand minimization would go no further. That's
> fine if there's no deeper theory about what's happening in this bug.

Thanks for the review!

I don't have a strong opinion between layout tests or unit tests. I've included
the unit test given that it's faster and easier to debug.

[chongz, 2016-12-22 18:50:03]

The CQ bit was checked by chongz@chromium.org

[chongz, 2016-12-22 18:50:03]

The patchset sent to the CQ was uploaded after l-g-t-m from
xiaochengh@chromium.org, dominicc@chromium.org
Link to the patchset: https://codereview.chromium.org/2595783002/#ps120001
(title: "dominicc's suggestion: Use unit test instead of layout test")

[commit-bot: I haz the power, 2016-12-22 18:50:26]

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

[commit-bot: I haz the power, 2016-12-22 18:54:20]

CQ is committing da patch.

Bot data: {"patchset_id": 120001, "attempt_start_ts": 1482432603019690,
"parent_rev": "ab2f32a5504f569726f3b85b61b88bc095519190", "commit_rev":
"5a8143410c67c68b0fa60b653453c5b7fea0cfad"}

[commit-bot: I haz the power, 2016-12-22 18:54:47]

Description was changed from

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks()|

The root cause is we are removing & re-inserting children nodes during
|CompositeEditCommand::removeNodePreservingChildren()|, which means if the child
contains style "* {-webkit-user-modify: read-write;}" we won't be able to
re-insert
it back as parent has lost editable attribute as soon as we've removed it.

BUG=675727
==========

to

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks()|

The root cause is we are removing & re-inserting children nodes during
|CompositeEditCommand::removeNodePreservingChildren()|, which means if the child
contains style "* {-webkit-user-modify: read-write;}" we won't be able to
re-insert
it back as parent has lost editable attribute as soon as we've removed it.

BUG=675727

Review-Url: https://codereview.chromium.org/2595783002
==========

[commit-bot: I haz the power, 2016-12-22 18:54:48]

Committed patchset #4 (id:120001)

[commit-bot: I haz the power, 2016-12-22 18:57:08]

Description was changed from

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks()|

The root cause is we are removing & re-inserting children nodes during
|CompositeEditCommand::removeNodePreservingChildren()|, which means if the child
contains style "* {-webkit-user-modify: read-write;}" we won't be able to
re-insert
it back as parent has lost editable attribute as soon as we've removed it.

BUG=675727

Review-Url: https://codereview.chromium.org/2595783002
==========

to

==========
[Editing] Add null check in |DeleteSelectionCommand::removeRedundantBlocks()|

The root cause is we are removing & re-inserting children nodes during
|CompositeEditCommand::removeNodePreservingChildren()|, which means if the child
contains style "* {-webkit-user-modify: read-write;}" we won't be able to
re-insert
it back as parent has lost editable attribute as soon as we've removed it.

BUG=675727

Committed: https://crrev.com/3c4ea2111cb111f66c87f8cd6bf3909eeaa15c9b
Cr-Commit-Position: refs/heads/master@{#440459}
==========

[commit-bot: I haz the power, 2016-12-22 18:57:10]

Patchset 4 (id:??) landed as
https://crrev.com/3c4ea2111cb111f66c87f8cd6bf3909eeaa15c9b
Cr-Commit-Position: refs/heads/master@{#440459}