Backed out changeset 3a1f27080f9c (bug 906811) for Linux mochitest failures.
Backed out 2 changesets (bug 909447, bug 909441) for jit-test failures on a CLOSED TREE.

Backed out changeset 3300c750cd53 (bug 909447)
Backed out changeset b1b242a80ef7 (bug 909441)