Revert of DevTools: do not mute the protocol channel while reattaching.

Revert of DevTools: do not mute the protocol channel while reattaching. (patchset #1 id:1 of https://codereview.chromium.org/945303002/)

Reason for revert:
DevToolsSanityTest.TestReattachAfterCrash is flaky on OSX 10.6 after this patch

Original issue's description:
> DevTools: do not mute the protocol channel while reattaching.
> Otherwise sync notifications are not going through.
> 
> BUG=460697
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=190745

TBR=dgozman@chromium.org,yurys@chromium.org,pfeldman@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=460697, 461616
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=190817

[sergeyv, 2015-02-25 10:38:41]

Created Revert of DevTools: do not mute the protocol channel while reattaching.

[commit-bot: I haz the power, 2015-02-25 10:39:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/958573002/1

[commit-bot: I haz the power, 2015-02-25 10:40:24]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=190817

[sergeyv, 2015-02-25 14:49:11]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/959723002/ by sergeyv@chromium.org.

The reason for reverting is: DevToolsSanityTest.TestReattachAfterCrash doesn't
check anything now, and this patch wasn't an origin of the flakiness on OSX
10.6. DevToolsSanityTest.TestReattachAfterCrash was disabled, so I reland
original patch.
.