Backed out 3 changesets (bug 1033340) for xpcshell failures.

Backed out changeset cad29a5b752d (bug 1033340)
Backed out changeset 284590145d2d (bug 1033340)
Backed out changeset 34182c54281a (bug 1033340)
Bug 1018234 - Reference count fontFaces. r=jfkthame, a=sledru
Bug 1027268 - Remove unnecessary timeout from test_bug391747.html to fix intermittent failures. r=mats, a=test-only