Only use it if no native requestAnimationFrame function is available. This should improve performance on mobile devices.
Animation methods get their own module, giving methods more sensible names: * `OpenLayers.Animation.requestFrame` (was `OpenLayers.Util.requestAnimationFrame`) * `OpenLayers.Animation.start` (was `OpenLayers.Util.startAnimation`) * `OpenLayers.Animation.stop` (was `OpenLayers.Util.stopAnimation`)