Backed out changeset 7e0f13fbecd3 (bug 983610)
Backed out changeset 246f001547ac (bug 981085)
Backed out changeset 81f230994acd (bug 980502) for hopefully fixing gi tests
Bug 962314 - Create nsIXULAppinfo.processID for obtaining Firefox PID; r=bsmedberg

--HG--
extra : rebase_source : 36536f7ed561dda55bc067a4d0d9ddef790bed17
Bug 986764: don't leak a thread for every getUserMedia doorhanger r=jib
Bug 986764: release all webrtc sub-modules before deleting engine r=gcp