Measure usage of Document.createTouch()

Measure usage of Document.createTouch()

This is for the same reason as the init*Event() methods, to know if
making all the arguments non-optional is likely safe or not:
https://codereview.chromium.org/1215893006

Also remove the webkit prefixes on the arguments, as the corresponding
attribute are now unprefixed on the Touch interface.

BUG=460722
R=rbyers@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=198595

[philipj_slow, 2015-07-08 22:00:34]

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

[commit-bot: I haz the power, 2015-07-08 22:01:04]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1227833002/1

[Rick Byers, 2015-07-08 22:10:33]

lgtm

[Rick Byers, 2015-07-08 22:11:05]

On 2015/07/08 22:10:33, Rick Byers wrote:
> lgtm

FWIW, from other evidence (eg. lack of good interop/specs here) I expect this to
be extremely low.

[philipj_slow, 2015-07-08 22:17:19]

On 2015/07/08 22:11:05, Rick Byers wrote:
> On 2015/07/08 22:10:33, Rick Byers wrote:
> > lgtm
> 
> FWIW, from other evidence (eg. lack of good interop/specs here) I expect this
to
> be extremely low.

Sounds promising!

[philipj_slow, 2015-07-08 22:17:26]

The CQ bit was unchecked by philipj@opera.com

[philipj_slow, 2015-07-09 11:00:53]

The CQ bit was checked by philipj@opera.com

[commit-bot: I haz the power, 2015-07-09 11:01:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1227833002/1

[commit-bot: I haz the power, 2015-07-09 11:52:07]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=198595