This is mostly self-explanatory. However, the patch also contains some minor
changes to frame scripts which expect to be able to call message manager
methods with a null target object, which stops working when they stop being
global objects.
MozReview-Commit-ID: HDT2RvK3F3L
--HG--
extra : rebase_source : bb3ce8861a261ff1bc28a28b3ff88ba0deaef552
Kris Maglione