Workaround 75604 for m15

Workaround 75604 for m15

The double notification is what causes the crash here: eliminating it should prevent the crash; and in all examples of this I've seen to date, it should be good enough.  By the time this crash happens, the ScriptRunner has already set a timer that will remove this element as a listener to the cachedscript.

However, I don't have a full fix yet (I'm working on a really reliably repo, even), but I do have a reproduction which works locally on a linux machine, and this fix both eliminates the crash in that case, and seems to still keep script heavy sites working.

I propose this as a workaround, for now, and to re-evaluate it once we have a better reproduction, and a proper fix that just stops the double notification.

BUG=75604
TEST=tested manually

[Nate Chapin, 2011-10-20 19:57:24]

LGTM.