[LayoutNG] Avoid creating empty LineBoxData in NGLineBuilder

[LayoutNG] Avoid creating empty LineBoxData in NGLineBuilder

Empty LineBoxData produces empty BidiRunList, which confuses
LayoutBlockFlow::constructLine() in CopyFragmentDataToLayoutBlockFlow().

There are cases where we need empty line boxes, such as when the caret
is set while editing. Such cases need to be revisited in future.

This is part of the effort to layout Wikipedia main page[1] with
LayoutNGInline runtime flag enabled.

[1] https://en.wikipedia.org/wiki/Main_Page

BUG=636993
Review-Url: https://codereview.chromium.org/2676883002
Cr-Commit-Position: refs/heads/master@{#448099}
Committed: https://chromium.googlesource.com/chromium/src/+/827d43cc4695df6291f3f30dade899aaf93665fd

[kojii, 2017-02-03 19:53:24]

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

[commit-bot: I haz the power, 2017-02-03 19:54:07]

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

[kojii, 2017-02-03 19:58:48]

Description was changed from

==========
ngemptyline

BUG=
==========

to

==========
[LayoutNG] Avoid creating empty LineBoxData in NGLineBuilder

Empty LineBoxData produces empty BidiRunList, which confuses
LayoutBlockFlow::constructLine() in CopyFragmentDataToLayoutBlockFlow().

There are cases where we need empty line boxes, such as when the caret
is set while editing. Such cases need to be revisited in future.

This is part of the effort to layout Wikipedia main page[1] with
LayoutNGInline runtime flag enabled.

[1] https://en.wikipedia.org/wiki/Main_Page

BUG=636993
==========

[kojii, 2017-02-03 19:59:09]

kojii@chromium.org changed reviewers:
+ eae@chromium.org

[kojii, 2017-02-03 19:59:10]

PTAL.

[eae, 2017-02-03 20:53:52]

LGTM

[commit-bot: I haz the power, 2017-02-03 21:43:12]

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

[commit-bot: I haz the power, 2017-02-03 21:43:13]

Dry run: This issue passed the CQ dry run.

[kojii, 2017-02-03 21:43:38]

The CQ bit was checked by kojii@chromium.org

[commit-bot: I haz the power, 2017-02-03 21:44:02]

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, 2017-02-03 22:48:29]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1486158218993030, "parent_rev":
"9c3cf47241e4a45b0e8ec2a5ca8e487d028c4bb3", "commit_rev":
"827d43cc4695df6291f3f30dade899aaf93665fd"}

[commit-bot: I haz the power, 2017-02-03 22:49:02]

Description was changed from

==========
[LayoutNG] Avoid creating empty LineBoxData in NGLineBuilder

Empty LineBoxData produces empty BidiRunList, which confuses
LayoutBlockFlow::constructLine() in CopyFragmentDataToLayoutBlockFlow().

There are cases where we need empty line boxes, such as when the caret
is set while editing. Such cases need to be revisited in future.

This is part of the effort to layout Wikipedia main page[1] with
LayoutNGInline runtime flag enabled.

[1] https://en.wikipedia.org/wiki/Main_Page

BUG=636993
==========

to

==========
[LayoutNG] Avoid creating empty LineBoxData in NGLineBuilder

Empty LineBoxData produces empty BidiRunList, which confuses
LayoutBlockFlow::constructLine() in CopyFragmentDataToLayoutBlockFlow().

There are cases where we need empty line boxes, such as when the caret
is set while editing. Such cases need to be revisited in future.

This is part of the effort to layout Wikipedia main page[1] with
LayoutNGInline runtime flag enabled.

[1] https://en.wikipedia.org/wiki/Main_Page

BUG=636993

Review-Url: https://codereview.chromium.org/2676883002
Cr-Commit-Position: refs/heads/master@{#448099}
Committed:
https://chromium.googlesource.com/chromium/src/+/827d43cc4695df6291f3f30dade8...
==========

[commit-bot: I haz the power, 2017-02-03 22:49:04]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/827d43cc4695df6291f3f30dade8...