Bug 884133: Kill sAppContext in GeckoApp. [r=blassey]

--HG--
extra : rebase_source : 28ce06926299a7d6c9f1413a9de89ea535ae60a3
Bug 885361 - Add shell option to hide functions that are unsafe for fuzzers. r=terrence
bug 880246: move EXTRA_PP_COMPONENTS to mozbuild (cleanup). r=mshal