If a page is preventing the default on a mouse down, a snapshotted plugin can never restart. We need to bypass the normal event processing mechanism in this case and notice when we see a mouseup that was associated with a mousedown in the snapshot. This won't actually trigger any user-side code, just restart the snapshotted plugin.
Created attachment 195737 [details]
Committed r147240: <http://trac.webkit.org/changeset/147240>