[Files app] Fix closure warnings

Closure only outputs warnings when there is at least one error. I
noticed this warnings when working in other CL.

These were introduced on ES6 class conversion CL:1588066

Change-Id: I66418a5f4d37b3bb3bf9ed0f1e0819c5df8538a4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1593880
Auto-Submit: Luciano Pacheco <lucmult@chromium.org>
Reviewed-by: Alex Danilo <adanilo@chromium.org>
Commit-Queue: Luciano Pacheco <lucmult@chromium.org>
Cr-Commit-Position: refs/heads/master@{#656303}

ui/file_manager/file_manager/common/js/importer_common.js

@@ -726,12 +726,9 @@ importer.Logger.prototype.catcher;
  * @implements {importer.Logger}
  * @final
  *
- * @param {!Promise<!FileEntry>} fileEntryPromise
  */
 importer.RuntimeLogger = class {
   /**
-   * @implements {importer.Logger}
-   *
    * @param {!Promise<!FileEntry>} fileEntryPromise
    */
   constructor(fileEntryPromise) {