Measure the impact of a propsed change to createAttribute()

Measure the impact of a propsed change to createAttribute()

There is a proposal to lowercase name in HTML documents:
https://bugzilla.mozilla.org/show_bug.cgi?id=1165851#c34

The counter in Document::createAttribute will catch any case where the
change would be observable, providing an upper limit to the risk.

The counter in Element::setAttributeNode is a reasonable proxy for the
case which is most likely problematic, namely trying to set a camelCase
Attr created by an HTML document on a non-HTML element, likely SVG, as
suggested by Boris Zbarsky:
https://bugzilla.mozilla.org/show_bug.cgi?id=1175031#c5

(The source of the Attr object need not be createAttribute, but extra
bookkeeping to determine that would either increase sizeof(Attr) or
require a new NodeFlags entry, so don't do that for now.)

BUG=502301
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=197549

[philipj_slow, 2015-06-19 17:02:53]

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

[commit-bot: I haz the power, 2015-06-19 17:03:26]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1195583002/1

[philipj_slow, 2015-06-19 17:04:17]

philipj@opera.com changed reviewers:
+ dominicc@chromium.org

[philipj_slow, 2015-06-19 17:04:17]

PTAL and CQ? (UseCounter.h is prone to conflicts)

[commit-bot: I haz the power, 2015-06-19 17:19:19]

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

[commit-bot: I haz the power, 2015-06-19 17:19:20]

Dry run: Try jobs failed on following builders:
  mac_blink_compile_dbg on tryserver.blink (JOB_FAILED,
http://build.chromium.org/p/tryserver.blink/builders/mac_blink_compile_dbg/bu...)

[philipj_slow, 2015-06-19 17:33:24]

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

[commit-bot: I haz the power, 2015-06-19 17:34:04]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1195583002/20001

[commit-bot: I haz the power, 2015-06-19 19:05:21]

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

[commit-bot: I haz the power, 2015-06-19 19:05:22]

Dry run: This issue passed the CQ dry run.

[philipj_slow, 2015-06-19 20:25:58]

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

[commit-bot: I haz the power, 2015-06-19 20:26:26]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1195583002/40001

[commit-bot: I haz the power, 2015-06-19 23:48:10]

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

[commit-bot: I haz the power, 2015-06-19 23:48:11]

Dry run: This issue passed the CQ dry run.

[dominicc (has gone to gerrit), 2015-06-22 01:07:10]

The CQ bit was checked by dominicc@chromium.org

[dominicc (has gone to gerrit), 2015-06-22 01:07:11]

lgtm

[commit-bot: I haz the power, 2015-06-22 01:07:24]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1195583002/40001

[commit-bot: I haz the power, 2015-06-22 02:58:05]

Committed patchset #3 (id:40001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=197549