Revert of Enable ServiceWorkerPerformanceTimeline flag for stable

Revert of Enable ServiceWorkerPerformanceTimeline flag for stable (patchset #1 id:1 of https://codereview.chromium.org/1203953002/)

Reason for revert:
This shipped new prefixed APIs:
https://groups.google.com/a/chromium.org/d/msg/blink-dev/htsW078UcFA/2cel1auAH60J

Original issue's description:
> 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

BUG=465640, 465641, 465643

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

Created Revert of Enable ServiceWorkerPerformanceTimeline flag for stable

[philipj_slow, 2015-07-24 06:52:47]

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

[commit-bot: I haz the power, 2015-07-24 06:53:34]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1255813002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1255813002/1

[commit-bot: I haz the power, 2015-07-24 06:58:27]

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

[commit-bot: I haz the power, 2015-07-24 06:58:27]

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...)
  mac_blink_rel on tryserver.blink (JOB_FAILED,
http://build.chromium.org/p/tryserver.blink/builders/mac_blink_rel/builds/63855)