Clarify comment

src/ol/interaction/dragrotateandzoominteraction.js

@@ -50,8 +50,9 @@ ol.interaction.DragRotateAndZoom.prototype.handleDrag =
       browserEvent.offsetX - size.width / 2,
       size.height / 2 - browserEvent.offsetY);
   var theta = Math.atan2(delta.y, delta.x);
-  // FIXME this should use map.withFrozenRendering but an assertion fails :-(
   map.requestRenderFrame();
+  // FIXME the calls to map.rotate and map.zoomToResolution should use
+  // map.withFrozenRendering but an assertion fails :-(
   map.rotate(this.startRotation_, -theta);
   var resolution = this.startRatio_ * delta.magnitude();
   map.zoomToResolution(resolution);