Remove AttributeCollection's findIndex(Attr*) by using QualifiedName

Remove AttributeCollection's findIndex(Attr*) by using QualifiedName

The internal Attribute and AttributeCollection need not know anything
about the web-exposed Attr.

Since Attr::qualifiedName() is not just a trivial getter, calling that
outside of the loop is probably a good idea anyway.

Committed: https://crrev.com/1cc8b43904b9ea7ad6058337e56ddca92b1c74fa
Cr-Commit-Position: refs/heads/master@{#361221}

[philipj_slow, 2015-11-23 15:00:32]

The CQ bit was checked by philipj@opera.com to run a CQ dry run

[commit-bot: I haz the power, 2015-11-23 15:00:49]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1467143004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1467143004/1

[commit-bot: I haz the power, 2015-11-23 16:11:39]

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

[commit-bot: I haz the power, 2015-11-23 16:11:39]

Dry run: This issue passed the CQ dry run.

[philipj_slow, 2015-11-23 16:15:57]

philipj@opera.com changed reviewers:
+ sigbjornf@opera.com

[philipj_slow, 2015-11-23 16:15:57]

PTAL. I'm looking into
https://code.google.com/p/chromium/issues/detail?id=502301 and finding little
things like this.

[sof, 2015-11-23 21:28:43]

lgtm.

The redundancy of that findIndex() overload made more apparent by the b829784
refactoring.

[philipj_slow, 2015-11-23 23:28:44]

The CQ bit was checked by philipj@opera.com

[commit-bot: I haz the power, 2015-11-23 23:30:22]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1467143004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1467143004/1

[commit-bot: I haz the power, 2015-11-23 23:51:24]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-23 23:52:09]

Patchset 1 (id:??) landed as
https://crrev.com/1cc8b43904b9ea7ad6058337e56ddca92b1c74fa
Cr-Commit-Position: refs/heads/master@{#361221}