Remove an inaccurate comment

src/annotator/bucket-bar-client.js

@@ -65,8 +65,6 @@ export class BucketBarClient {
 
     this._updatePending = true;
     requestAnimationFrame(() => {
-      // Computing anchor positions may be expensive when there are many
-      // annotations or a forced layout reflow
       const positions = computeAnchorPositions(this._anchors);
       this._hostRPC.call('anchorsChanged', positions);
       this._updatePending = false;