Backed out changeset b92529577644 (bug 895395) on suspicion of causing shutdown hangs on OS X
Backed out changeset 998d2d5e743d (bug 919878) on suspicion of causing shutdown hangs on OS X
Backed out changeset 77f53f9d3099 (bug 935784) on suspicion of causing shutdown hangs on OS X
Merge mozilla-central and b2g-inbound