message: fixes for Dubious switch fallthrough case in undo-redo
  break statement was missing before fall through / default in case for MergeTreeDeltaType.ANNOTATE
diff: @@ -124,7 +124,7 @@ export class SharedSegmentSequenceRevertible implements IRevertible {
  tracked.propertyDelta,
  undefined);
  }
  - // fallthrough
  + break;
  default:
  throw new Error("operationt type not revertible");
  }
  