Add pref 'memory.free_dirty_pages' from https://bugzilla.mozilla.org/show_bug.cgi?id=805855
Add pref 'memory.free_dirty_pages' from https://bugzilla.mozilla.org/show_bug.cgi?id=805855

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