Bug 928056 - Do not pause for background compilation before ggc; r=bhackett,r=billm

--HG--
extra : rebase_source : 60b4f5539f30213836c3acc87f8aa88404dd52eb
Bug 929065 - Fix an oom handling issue in ion compilation; r=bhackett

--HG--
extra : rebase_source : a2996447791b60ca53d02f7eb514143370c232b0