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

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

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extra : rebase_source : a2996447791b60ca53d02f7eb514143370c232b0
Bug 925916 - Revert computThis() to thisv(). r=bz

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extra : rebase_source : 9de03d5a7c8867f92984eee80a185ca3f3c0f764