Well, Firefox is not Chrome. Firefox usually supports things more completely than Chrome, partially because that's just what they do, they safeguard webstandards, so delivering a standards-compliant browser is a main-goal, but in large parts also because the community will make Mozilla go the extra mile with code contributions, if they don't do it themselves.
And a Mozilla dev, Manishearth, has commented above that he is in fact currently looking into making it configurable.
And a Mozilla dev, Manishearth, has commented above that he is in fact currently looking into making it configurable.