Disable PGO for ObjectImpl::nativeLookup (bug 844580, r=billm). a=lsblakk
Bug 850730 - Do not add browser handlers to about:blank. r=gavin, a=bajaj
Bug 851436 - Revert tab strip logic by backing out patches for bug 837486, bug 649654, and bug 821859. r=dao, a=bajaj