Enable ServiceWorkerPerformanceTimeline flag for stable

Enable ServiceWorkerPerformanceTimeline flag for stable

This ships User Timing and Resource Timing in Workers, and workerStart
attribute of Resource Timing.

I think it's safe to enable it now; User Timing and workerStart have
landed over 2 weeks ago. Resource Timing part is new, but I only added
main thread to worker plumbing on the existing stable implementation.

Intent to Implement and Ship:
https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/htsW078UcFA

BUG=465640, 465641, 465643
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=197722

[Kunihiko Sakamoto, 2015-06-24 07:17:53]

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

[tkent, 2015-06-24 07:21:18]

We usually don't enable a feature just before a branch point.  Do you think it's
safe?  If so, please write a reason of the safety in the CL description.

[Kunihiko Sakamoto, 2015-06-24 07:55:40]

On 2015/06/24 07:21:18, tkent wrote:
> We usually don't enable a feature just before a branch point.  Do you think
it's
> safe?  If so, please write a reason of the safety in the CL description.

Updated the CL description. Does it look good to you?

[tkent, 2015-06-24 07:57:48]

lgtm

[Kunihiko Sakamoto, 2015-06-24 08:00:42]

Thanks!

[Kunihiko Sakamoto, 2015-06-24 08:00:46]

The CQ bit was checked by ksakamoto@chromium.org

[commit-bot: I haz the power, 2015-06-24 08:01:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1203953002/1

[commit-bot: I haz the power, 2015-06-24 09:34:45]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=197722

[philipj_slow, 2015-07-24 06:50:58]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1255813002/ by philipj@opera.com.

The reason for reverting is: This shipped new prefixed APIs:
https://groups.google.com/a/chromium.org/d/msg/blink-dev/htsW078UcFA/2cel1auA....