Fix appcache/fallback test race exposed by the Blink Scheduler.

Fix appcache/fallback test race exposed by the Blink Scheduler.

The blink scheduler exposed a race where the onnoupdate event could happen
before the iframe has been loaded, causing the test to become flaky. This
fix replaces the use of onnoupdate with an onload event on the iframe.

Also remove linux specific expectation since the linux expected result is
now the same as all other platforms.

BUG=432129
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=185279

[rmcilroy, 2014-11-12 23:19:47]

rmcilroy@chromium.org changed reviewers:
+ japhet@chromium.org

[rmcilroy, 2014-11-12 23:19:47]

Nate: could you please take a look, thanks.

I'm not sure if it is important that the test checks that onnoupdate is called
for the iframe load - if not there is a simpler fix in patch-set-1 which only
waits for onload before running test5.  Let me know which you prefer.

[rmcilroy, 2014-11-12 23:24:48]

Patchset #2 (id:20001) has been deleted

[Nate Chapin, 2014-11-13 00:10:50]

lgtm

[rmcilroy, 2014-11-13 08:18:20]

The CQ bit was checked by rmcilroy@chromium.org

[commit-bot: I haz the power, 2014-11-13 08:18:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/720963002/40001

[commit-bot: I haz the power, 2014-11-13 09:37:45]

Committed patchset #2 (id:40001) as 185279