[WebSocket] Remove release assertions that are no longer needed.

[WebSocket] Remove release assertions that are no longer needed.

[1] and [2] placed release assertions to investigate a crash bug and provide a
workaround solution. Now the right fix has been landed and we can remove them.

1: https://crrev.com/4b823461db8e2bc8faf5438be4cc30f6a9401aef
2: https://crrev.com/a6af78bd57595484765d2a3ca18f38fa135be796

BUG=550632
Committed: https://crrev.com/c9feab14e31c6e5bbaaef2461529f7b20df47ac6
Cr-Commit-Position: refs/heads/master@{#361320}

[yhirano, 2015-11-19 08:43:42]

yhirano@chromium.org changed reviewers:
+ tyoshino@chromium.org

[haraken, 2015-11-24 06:26:14]

LGTM

[sof, 2015-11-24 07:29:17]

sigbjornf@opera.com changed reviewers:
+ sigbjornf@opera.com

[sof, 2015-11-24 07:29:17]

(the prefinalizers added here didn't serve a purpose, as they weren't
registered.. )

[tyoshino (SeeGerritForStatus), 2015-11-24 08:33:39]

lgtm

[yhirano, 2015-11-24 10:05:25]

The CQ bit was checked by yhirano@chromium.org

[commit-bot: I haz the power, 2015-11-24 10:06:16]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1456463002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1456463002/1

[commit-bot: I haz the power, 2015-11-24 11:55:37]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-24 11:56:18]

Patchset 1 (id:??) landed as
https://crrev.com/c9feab14e31c6e5bbaaef2461529f7b20df47ac6
Cr-Commit-Position: refs/heads/master@{#361320}