Comment 32 for bug 250769

(In reply to comment #31)
Automated testing depends on having a windowless plugin in our source tree
(bug 386144).

I've manually tested this patch with Swfdec on the problem sites reported
here, Geoff Norton has tested the Moonlight plugin (comment #22) on their
testcases (including attachment attachment 326988), and Mike Melanson has
tested the Adobe plugin (comment #28).