Use nsCrossSiteListenerProxy.h helpers to implement CORS support.
Several CORS fixes and lots of CORS tests.
Fixes:
Use empty string stream if response has no stream.
Parse Access-Control-Expose-Headers correctly.
Copy over remaining InternalRequest constructor attributes and set unsafe request flag.
Call FailWithNetworkError() in more cases.
Add non-simple Request headers to unsafeHeaders list for CORS check.
Do not AsyncOpen channel directly when CORS preflight is required.
Fix check for simple request method (was checking the opposite condition).
--HG--
extra : rebase_source : 4b08f6a5959e470394c88249b39464b3b7d20948
