Add comment about flush order when re-debouncing

lib/utils/debounce.js

@@ -48,6 +48,10 @@ export class Debouncer {
     if (this.isActive()) {
       this._cancelAsync();
       this._timer = null;
+      // Canceling a debouncer removes its spot from the flush queue,
+      // so if a debouncer is manually canceled and re-debounced, it
+      // will reset its flush order (this is a very minor difference from 1.x)
+      // Re-debouncing via the `debounce` API retains the 1.x FIFO flush order
       debouncerQueue.delete(this);
     }
   }