Backed out changeset c39ede0eea8f (bug 844805) for perf regressions (bug 887266). no_r=regression.
Backed out changeset 5428fa083db3 (bug 844805) for perf regressions (bug 887266). no_r=regression.
Backed out changeset 3f152e51be2b (bug 844805) for perf regressions (bug 887266). no_r=regression.