Clean up and tighten security.
Mainly cleanup of VERSION_SKEW tag. Also set SWFBridgeRequest.requestor in SystemManager.dispatchEventFromSWFBridges() to make sure there is no way a bridge could leak out to an app that shouldn?\226?\128?\153t get it. For example we don?\226?\128?\153t want A.3 to send its parent bridge to A.3.2 or A.3.3.
QE: Yes, all Marshall Plan tests should still pass.
Checkintests: Yes and Marshall Plan tests.