Bug 734691 - Bustage fix on a CLOSED TREE. r=bustage

--HG--
extra : rebase_source : 9cacf4f98477aade4d3367f6ddbbcac2163844b6
Backout 138ea79ea71a (bug 854288) and aa9b27b090db (bug 852032) for xpcshell bustage on a CLOSED TREE