Fix mistaken use of promise in multiple-register.html

Fix mistaken use of promise in multiple-register.html

service_worker_unregister_and_done was outside of the .then chain, so it
would execute early and the test passes regardless of the assertions.

BUG=395928
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=179020

[nhiroki, 2014-07-28 08:05:23]

LGTM.

Can you remove the suppression referred to in http://crbug.com/397892 if the
crash never happens after this change?

[falken, 2014-07-28 08:24:23]

On 2014/07/28 08:05:23, nhiroki wrote:
> LGTM.
> 
> Can you remove the suppression referred to in http://crbug.com/397892 if the
> crash never happens after this change?

Thanks, done. Of course, it's still a bug in our C++ code to crash on the
the original test.

[falken, 2014-07-28 08:24:48]

The CQ bit was checked by falken@chromium.org

[commit-bot: I haz the power, 2014-07-28 08:25:05]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/falken@chromium.org/426563003/20001

[commit-bot: I haz the power, 2014-07-28 09:27:15]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  mac_blink_compile_dbg on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/mac_blink_compile_dbg/bu...)

[commit-bot: I haz the power, 2014-07-28 09:36:01]

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

[commit-bot: I haz the power, 2014-07-28 09:36:02]

Try jobs failed on following builders:
  mac_blink_compile_dbg on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/mac_blink_compile_dbg/bu...)

[falken, 2014-07-28 10:45:27]

The CQ bit was checked by falken@chromium.org

[commit-bot: I haz the power, 2014-07-28 10:46:13]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/falken@chromium.org/426563003/20001

[commit-bot: I haz the power, 2014-07-28 10:54:31]

Change committed as 179020