/**
 * Provides requestAnimationFrame in a cross browser way.
 * http://paulirish.com/2011/requestanimationframe-for-smart-animating/
 */

if ( !window.requestAnimationFrame ) {

  window.requestAnimationFrame = ( function() {

    return window.webkitRequestAnimationFrame ||
    window.mozRequestAnimationFrame ||
    window.oRequestAnimationFrame ||
    window.msRequestAnimationFrame ||
    function( /* function FrameRequestCallback */ callback, /* DOMElement Element */ element ) {

      window.setTimeout( callback, 1000 / 60 );

    };

  } )();

}