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
Committed: https://crrev.com/94212593f88dbdb92ea8f090b28cc9a5c4a2c8e3
git-svn-id: svn://svn.chromium.org/blink/trunk@199493 bbb929c8-8fbe-4397-9dbb-9b2b20218538

[Kunihiko Sakamoto, 2015-07-24 10:15:52]

The CQ bit was checked by ksakamoto@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-07-24 10:16:08]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1254803002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1254803002/1

[Kunihiko Sakamoto, 2015-07-24 10:24:18]

ksakamoto@chromium.org changed reviewers:
+ philipj@opera.com, tkent@chromium.org

[Kunihiko Sakamoto, 2015-07-24 10:24:18]

This is going to be merged to M45 to avoid shipping prefixed APIs.
We're re-aiming at M46.

[philipj_slow, 2015-07-24 11:08:14]

lgtm

[commit-bot: I haz the power, 2015-07-24 11:35:04]

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

[commit-bot: I haz the power, 2015-07-24 11:35:05]

Dry run: Try jobs failed on following builders:
  win_blink_rel on tryserver.blink (JOB_FAILED,
http://build.chromium.org/p/tryserver.blink/builders/win_blink_rel/builds/71486)

[Kunihiko Sakamoto, 2015-07-27 01:15:04]

The CQ bit was checked by ksakamoto@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-07-27 01:15:12]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1254803002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1254803002/1

[Kunihiko Sakamoto, 2015-07-27 03:46:42]

The CQ bit was checked by ksakamoto@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-07-27 03:46:55]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1254803002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1254803002/20001

[Kunihiko Sakamoto, 2015-07-27 06:01:19]

Kent-san, PTAL

[tkent, 2015-07-27 06:04:42]

lgtm

[commit-bot: I haz the power, 2015-07-27 07:01:14]

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

[commit-bot: I haz the power, 2015-07-27 07:01:14]

Dry run: This issue passed the CQ dry run.

[Kunihiko Sakamoto, 2015-07-27 07:15:53]

The CQ bit was checked by ksakamoto@chromium.org

[Kunihiko Sakamoto, 2015-07-27 07:15:53]

The patchset sent to the CQ was uploaded after l-g-t-m from philipj@opera.com
Link to the patchset: https://codereview.chromium.org/1254803002/#ps20001
(title: "Fix webexposed test")

[commit-bot: I haz the power, 2015-07-27 07:16:10]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1254803002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1254803002/20001

[commit-bot: I haz the power, 2015-07-27 07:19:50]

Committed patchset #2 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=199493

[commit-bot: I haz the power, 2015-09-23 11:47:57]

Patchset 2 (id:??) landed as
https://crrev.com/94212593f88dbdb92ea8f090b28cc9a5c4a2c8e3