Add pref canvas.hitregions.enabled from http://hg.mozilla.org/mozilla-central/rev/24f3ddfd7c48
Add pref canvas.hitregions.enabled from http://hg.mozilla.org/mozilla-central/rev/24f3ddfd7c48

MozillaSecurity/funfuzz,nth10sd/funfuzz,MozillaSecurity/funfuzz,nth10sd/funfuzz,nth10sd/funfuzz,MozillaSecurity/funfuzz