Revert of Move Event to oilpan's heap

Revert of Move Event to oilpan's heap (https://codereview.chromium.org/208173004/)

Reason for revert:
Seems likely to have caused a number of flaky failures in layout tests in oilpan builds:

Flakiness dashboard link: http://test-results.appspot.com/dashboards/flakiness_dashboard.html#group=%40ToT%20Blink&tests=http%2Ftests%2Fmedia%2Fmedia-source%2Fwebkitmediasource-closed-on-htmlmediaelement-destruction.html%2Csvg%2Fanimations%2Fsmil-leak-element-instances-noBaseValRef.svg%2Csvg%2Fanimations%2Fsmil-leak-element-instances.svg%2Csvg%2Fanimations%2Fsmil-leak-elements.svg

Example failure bot: http://build.chromium.org/p/chromium.webkit/builders/WebKit%20Linux%20Oilpan/builds/2770

Example failure:
--- /mnt/data/b/build/slave/WebKit_Linux_Oilpan/build/layout-test-results/svg/animations/smil-leak-element-instances-noBaseValRef-expected.txt
+++ /mnt/data/b/build/slave/WebKit_Linux_Oilpan/build/layout-test-results/svg/animations/smil-leak-element-instances-noBaseValRef-actual.txt
@@ -1 +1 @@
-PASS
+FAIL: -3 extra live node(s)




Original issue's description:
> Move Event to oilpan's heap
> 
> Now there is no test failing when I change RefCounted<Event> to RefCountedGarbageCollected<Event>. Thus this CL does the change.
> 
> BUG=340522
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=169941

TBR=oilpan-reviews@chromium.org,ager@chromium.org,wibling@chromium.org,haraken@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=340522
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=170092

[enne (OOO), 2014-03-26 20:17:17]

Created Revert of Move Event to oilpan's heap

[commit-bot: I haz the power, 2014-03-26 20:17:29]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/enne@chromium.org/213403004/1

[commit-bot: I haz the power, 2014-03-26 20:18:32]

Change committed as 170092

[sof, 2014-03-26 20:29:07]

Thanks for trying to clear out test failures.

Taking out this particular change isn't complete, and is problematic. i.e., both

  https://codereview.chromium.org/208743011/
  https://codereview.chromium.org/212933005/

assume that Event is garbage collected, so I wonder if this revert will create
instability.

[enne (OOO), 2014-03-26 20:30:34]

On 2014/03/26 20:29:07, sof wrote:
> Thanks for trying to clear out test failures.
> 
> Taking out this particular change isn't complete, and is problematic. i.e.,
both
> 
>   https://codereview.chromium.org/208743011/
>   https://codereview.chromium.org/212933005/
> 
> assume that Event is garbage collected, so I wonder if this revert will create
> instability.

Hmm.  Thanks for the followup.  I'll keep an eye out and revert the revert if I
see anything.

[sof, 2014-03-26 20:37:34]

On 2014/03/26 20:30:34, enne wrote:
> On 2014/03/26 20:29:07, sof wrote:
> > Thanks for trying to clear out test failures.
> > 
> > Taking out this particular change isn't complete, and is problematic. i.e.,
> both
> > 
> >   https://codereview.chromium.org/208743011/
> >   https://codereview.chromium.org/212933005/
> > 
> > assume that Event is garbage collected, so I wonder if this revert will
create
> > instability.
> 
> Hmm.  Thanks for the followup.  I'll keep an eye out and revert the revert if
I
> see anything.

Please see https://codereview.chromium.org/211933007/ 

(I picked the wrong DOMWindow CL in the above, the 2nd one should have been
https://codereview.chromium.org/211373002/ )

[enne (OOO), 2014-03-26 20:43:43]

I don't know much about oilpan at all.  Just to make sure I'm on the same page,
are you saying that it's likely that the tests that went broken just needed to
be updated, and that this patch shouldn't have been reverted?

[sof, 2014-03-26 20:57:23]

On 2014/03/26 20:43:43, enne wrote:
> I don't know much about oilpan at all.  Just to make sure I'm on the same
page,
> are you saying that it's likely that the tests that went broken just needed to
> be updated, and that this patch shouldn't have been reverted?

Yes, the pass conditions for those tests needs to be looked at further (e.g.,
perhaps go with what the initial patchset used --
https://codereview.chromium.org/211933007/#ps1)

How about marking them as failures in LayoutTests/OilpanExpectations for now &
undo the revert?

[enne (OOO), 2014-03-26 22:59:31]

A revert of this CL has been created in
https://codereview.chromium.org/213803002/ by enne@chromium.org.

The reason for reverting is: Original revert was too aggressive.  Failures are
just local to the test, and the original patch fixed bugs..