Revert of Fixing crash that can occur if signal is modified while firing.

Revert of Fixing crash that can occur if signal is modified while firing. (patchset #3 id:40001 of https://codereview.webrtc.org/2846593005/ )

Reason for revert:
Revealed a race condition (now reported by TSan), and breaks the scenario where a signal is deleted while firing.

Original issue's description:
> Fixing crash that can occur if signal is modified while firing.
> 
> The crash occurs if a slot causes the very next slot in iteration order
> to be disconnected.
> 
> BUG=webrtc:7527
> 
> Review-Url: https://codereview.webrtc.org/2846593005
> Cr-Commit-Position: refs/heads/master@{#17943}
> Committed: https://chromium.googlesource.com/external/webrtc/+/961c2adf1ea25bcc40ad64cae1ac2ea258e26de2

TBR=pthatcher@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:7527
Review-Url: https://codereview.webrtc.org/2847243006
Cr-Commit-Position: refs/heads/master@{#17947}
Committed: https://chromium.googlesource.com/external/webrtc/+/86746c475f146a9f830ceccc3b0f63be12ed8b4a

[Taylor Brandstetter, 2017-04-29 19:00:07]

The CQ bit was checked by deadbeef@webrtc.org

[Taylor Brandstetter, 2017-04-29 19:00:07]

Created Revert of Fixing crash that can occur if signal is modified while
firing.

[commit-bot: I haz the power, 2017-04-29 19:00:18]

CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.webrtc.org/...

[commit-bot: I haz the power, 2017-04-29 19:00:21]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1493492407265860, "parent_rev":
"e89ee4cace72694b612038b805d7053fb550ec1f", "commit_rev":
"86746c475f146a9f830ceccc3b0f63be12ed8b4a"}

[commit-bot: I haz the power, 2017-04-29 19:00:25]

Description was changed from

==========
Revert of Fixing crash that can occur if signal is modified while firing.
(patchset #3 id:40001 of https://codereview.webrtc.org/2846593005/ )

Reason for revert:
Revealed a race condition (now reported by TSan), and breaks the scenario where
a signal is deleted while firing.

Original issue's description:
> Fixing crash that can occur if signal is modified while firing.
> 
> The crash occurs if a slot causes the very next slot in iteration order
> to be disconnected.
> 
> BUG=webrtc:7527
> 
> Review-Url: https://codereview.webrtc.org/2846593005
> Cr-Commit-Position: refs/heads/master@{#17943}
> Committed:
https://chromium.googlesource.com/external/webrtc/+/961c2adf1ea25bcc40ad64cae...

TBR=pthatcher@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:7527
==========

to

==========
Revert of Fixing crash that can occur if signal is modified while firing.
(patchset #3 id:40001 of https://codereview.webrtc.org/2846593005/ )

Reason for revert:
Revealed a race condition (now reported by TSan), and breaks the scenario where
a signal is deleted while firing.

Original issue's description:
> Fixing crash that can occur if signal is modified while firing.
> 
> The crash occurs if a slot causes the very next slot in iteration order
> to be disconnected.
> 
> BUG=webrtc:7527
> 
> Review-Url: https://codereview.webrtc.org/2846593005
> Cr-Commit-Position: refs/heads/master@{#17943}
> Committed:
https://chromium.googlesource.com/external/webrtc/+/961c2adf1ea25bcc40ad64cae...

TBR=pthatcher@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:7527

Review-Url: https://codereview.webrtc.org/2847243006
Cr-Commit-Position: refs/heads/master@{#17947}
Committed:
https://chromium.googlesource.com/external/webrtc/+/86746c475f146a9f830ceccc3...
==========

[commit-bot: I haz the power, 2017-04-29 19:00:25]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/external/webrtc/+/86746c475f146a9f830ceccc3...