Reapplied changeset 31ff9550fba6 (bug 870073)
Bug 870768 - Disable verify url test. r=gbrown
Bug 870667.  Reinstate a way to turn off performance.timing bits using a pref.  r=smaug

This is used by the Tor project, for example.
Bug 870566.  Make dataset gets faster by spending less time messing with strings.  r=smaug