We want to land part3 of optimization levels already. Since this could improve some edge-cases. But we are not sure we can land everything in time for merge on Monday and be sure we have no regressions or backouts. It would be hard to maintain a bug across versions. So here we will land the preparation patches part1-3 (in FF28). And the rest will land in FF29.

Landed patch 1 - 3, r+ by jandem in bug 939614 https://hg.mozilla.org/integration/mozilla-inbound/rev/0443d213ad79 https://hg.mozilla.org/integration/mozilla-inbound/rev/03916ed4ced2 https://hg.mozilla.org/integration/mozilla-inbound/rev/e809fabe13e3

https://hg.mozilla.org/mozilla-central/rev/0443d213ad79 https://hg.mozilla.org/mozilla-central/rev/03916ed4ced2 https://hg.mozilla.org/mozilla-central/rev/e809fabe13e3