Fix emoji ZWJ and modifier sequence line breaking

Fix emoji ZWJ and modifier sequence line breaking

Line breaking positions returned from ICU would allow us to break emoji
sequences in the middle, leading to part of the sequence being shown as the
fallback emoji on the first line, the other part on the second
line. Until ICU implements this behavior we customize the line breaking
and reject those break suggestions.

Original isBreakValid implementation by Raph Levien, adapted to Blink
with permission, thank you!

BUG=593263
TEST=TextBreakIterator* unit tests in blink_platform_unittests

Committed: https://crrev.com/950933340685436d8d1d7b8f9d7767e95bcf96a6
Cr-Commit-Position: refs/heads/master@{#380619}

[drott, 2016-03-09 19:21:22]

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

[drott, 2016-03-09 19:21:45]

drott@chromium.org changed reviewers:
+ eae@chromium.org, kojii@chromium.org, leviw@chromium.org

[commit-bot: I haz the power, 2016-03-09 19:22:08]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1779693003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1779693003/1

[eae, 2016-03-09 19:31:45]

LGTM++

[commit-bot: I haz the power, 2016-03-09 20:07:55]

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

[commit-bot: I haz the power, 2016-03-09 20:07:55]

Dry run: Try jobs failed on following builders:
  win_chromium_rel_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_...)

[drott, 2016-03-10 08:07:57]

Windows build fix, removing u8, MSVC does not understand those

[drott, 2016-03-10 08:08:10]

The CQ bit was checked by drott@chromium.org

[drott, 2016-03-10 08:08:10]

The patchset sent to the CQ was uploaded after l-g-t-m from eae@chromium.org
Link to the patchset: https://codereview.chromium.org/1779693003/#ps20001
(title: "Windows build fix, removing u8, MSVC does not understand those")

[commit-bot: I haz the power, 2016-03-10 08:08:17]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1779693003/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1779693003/20001

[commit-bot: I haz the power, 2016-03-10 09:01:01]

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

[commit-bot: I haz the power, 2016-03-10 09:01:02]

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

[drott, 2016-03-10 09:38:58]

The CQ bit was checked by drott@chromium.org

[commit-bot: I haz the power, 2016-03-10 09:39:12]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1779693003/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1779693003/20001

[commit-bot: I haz the power, 2016-03-10 11:09:37]

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

[commit-bot: I haz the power, 2016-03-10 11:09:38]

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

[drott, 2016-03-10 17:48:36]

Fix out of bounds access in tests

[drott, 2016-03-10 17:49:42]

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

[commit-bot: I haz the power, 2016-03-10 17:50:13]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1779693003/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1779693003/40001

[drott, 2016-03-10 17:51:55]

eae@, if you have a moment to take another look, after the ASAN bot failure
alarm, I have to clamp triggerPos to the string length in the test, also I
removed the final assertion that was looking past the string length. I checked
that the tests still work reliably as regression tests.

[eae, 2016-03-10 18:23:13]

LGTM

[eae, 2016-03-10 18:23:31]

The CQ bit was unchecked by eae@chromium.org

[eae, 2016-03-10 18:23:37]

The CQ bit was checked by eae@chromium.org

[commit-bot: I haz the power, 2016-03-10 18:24:02]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1779693003/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1779693003/40001

[commit-bot: I haz the power, 2016-03-10 18:54:27]

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

[commit-bot: I haz the power, 2016-03-10 18:54:28]

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

[eae, 2016-03-10 20:00:35]

The CQ bit was checked by eae@chromium.org

[commit-bot: I haz the power, 2016-03-10 20:02:04]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1779693003/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1779693003/40001

[commit-bot: I haz the power, 2016-03-10 21:29:26]

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

[commit-bot: I haz the power, 2016-03-10 21:29:27]

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

[drott, 2016-03-10 21:41:03]

The CQ bit was checked by drott@chromium.org

[commit-bot: I haz the power, 2016-03-10 21:41:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1779693003/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1779693003/40001

[commit-bot: I haz the power, 2016-03-10 22:57:53]

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

[commit-bot: I haz the power, 2016-03-10 22:57:54]

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

[drott, 2016-03-11 06:58:40]

Rebased

[drott, 2016-03-11 06:58:45]

The CQ bit was checked by drott@chromium.org

[drott, 2016-03-11 06:58:45]

The patchset sent to the CQ was uploaded after l-g-t-m from eae@chromium.org
Link to the patchset: https://codereview.chromium.org/1779693003/#ps60001
(title: "Rebased")

[commit-bot: I haz the power, 2016-03-11 06:59:06]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1779693003/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1779693003/60001

[commit-bot: I haz the power, 2016-03-11 08:18:04]

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

[commit-bot: I haz the power, 2016-03-11 08:18:05]

Try jobs failed on following builders:
  linux_android_rel_ng on tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/linux_androi...)

[drott, 2016-03-11 12:22:23]

The CQ bit was checked by drott@chromium.org

[commit-bot: I haz the power, 2016-03-11 12:22:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1779693003/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1779693003/60001

[commit-bot: I haz the power, 2016-03-11 13:35:00]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2016-03-11 13:36:07]

Description was changed from

==========
Fix emoji ZWJ and modifier sequence line breaking

Line breaking positions returned from ICU would allow us to break emoji
sequences in the middle, leading to part of the sequence being shown as the
fallback emoji on the first line, the other part on the second
line. Until ICU implements this behavior we customize the line breaking
and reject those break suggestions.

Original isBreakValid implementation by Raph Levien, adapted to Blink
with permission, thank you!

BUG=593263
TEST=TextBreakIterator* unit tests in blink_platform_unittests
==========

to

==========
Fix emoji ZWJ and modifier sequence line breaking

Line breaking positions returned from ICU would allow us to break emoji
sequences in the middle, leading to part of the sequence being shown as the
fallback emoji on the first line, the other part on the second
line. Until ICU implements this behavior we customize the line breaking
and reject those break suggestions.

Original isBreakValid implementation by Raph Levien, adapted to Blink
with permission, thank you!

BUG=593263
TEST=TextBreakIterator* unit tests in blink_platform_unittests

Committed: https://crrev.com/950933340685436d8d1d7b8f9d7767e95bcf96a6
Cr-Commit-Position: refs/heads/master@{#380619}
==========

[commit-bot: I haz the power, 2016-03-11 13:36:08]

Patchset 4 (id:??) landed as
https://crrev.com/950933340685436d8d1d7b8f9d7767e95bcf96a6
Cr-Commit-Position: refs/heads/master@{#380619}