code: function() {
          var done = true,
              anim;
          for (anim in Transition._running) {
              if (Transition._running[anim]._runFrame) {
                  done = false;
                  Transition._running[anim]._runFrame();
              }
          }
  
          if (done) {
              Transition._stopTimer();
          }
      }
docs: /*
  Called per Interval to handle each animation frame.
  @method _runFrame
  @private
  @static