Avoid WTF::Vector::at() and operator[] in core/html.

Avoid WTF::Vector::at() and operator[] in core/html.

at() and operator[] are slow due to RELEASE_ASSERT. We can avoid the slowness by
range-based |for|.

This CL has no behavior changes except runtime performance.

BUG=668300
Committed: https://crrev.com/f5775c2f04c255de2fe9f68ff8444d3f987901a4
Cr-Commit-Position: refs/heads/master@{#437175}

[tkent, 2016-12-07 08:29:15]

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

[commit-bot: I haz the power, 2016-12-07 08:29:34]

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, 2016-12-07 09:45:12]

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

[commit-bot: I haz the power, 2016-12-07 09:45:13]

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

[tkent, 2016-12-07 23:26:53]

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

[commit-bot: I haz the power, 2016-12-07 23:27:42]

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

[tkent, 2016-12-08 00:07:38]

Patchset #1 (id:1) has been deleted

[tkent, 2016-12-08 00:47:31]

tkent@chromium.org changed reviewers:
+ hayato@chromium.org

[tkent, 2016-12-08 00:47:31]

hayato@, would you review this please?

[commit-bot: I haz the power, 2016-12-08 00:59:22]

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

[commit-bot: I haz the power, 2016-12-08 00:59:23]

Dry run: This issue passed the CQ dry run.

[hayato, 2016-12-08 03:06:49]

lgtm

[tkent, 2016-12-08 04:07:03]

The CQ bit was checked by tkent@chromium.org

[commit-bot: I haz the power, 2016-12-08 04:07:28]

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, 2016-12-08 04:12:18]

CQ is committing da patch.

Bot data: {"patchset_id": 20001, "attempt_start_ts": 1481170023819770,
"parent_rev": "6da41826c5d51c5d640459add4bd799050fc90e5", "commit_rev":
"01d69315c01accb21398931cd679afa4f1d9b58e"}

[commit-bot: I haz the power, 2016-12-08 04:13:37]

Committed patchset #1 (id:20001)

[commit-bot: I haz the power, 2016-12-08 04:17:59]

Description was changed from

==========
Avoid WTF::Vector::at() and operator[] in core/html.

at() and operator[] are slow due to RELEASE_ASSERT. We can avoid the slowness by
range-based |for|.

This CL has no behavior changes except runtime performance.

BUG=668300
==========

to

==========
Avoid WTF::Vector::at() and operator[] in core/html.

at() and operator[] are slow due to RELEASE_ASSERT. We can avoid the slowness by
range-based |for|.

This CL has no behavior changes except runtime performance.

BUG=668300

Committed: https://crrev.com/f5775c2f04c255de2fe9f68ff8444d3f987901a4
Cr-Commit-Position: refs/heads/master@{#437175}
==========

[commit-bot: I haz the power, 2016-12-08 04:18:00]

Patchset 1 (id:??) landed as
https://crrev.com/f5775c2f04c255de2fe9f68ff8444d3f987901a4
Cr-Commit-Position: refs/heads/master@{#437175}