Files.app: Fix closure compiler error in import_controller.js

BUG=None
TEST=None
TBR=smckay@chromium.org

Review URL: https://codereview.chromium.org/937093002

Cr-Commit-Position: refs/heads/master@{#317002}

ui/file_manager/file_manager/foreground/js/import_controller.js

@@ -440,7 +440,7 @@ importer.ClickSource = {
  */
 importer.RuntimeCommandWidget = function() {
 
-  /** @private {Element} */
+  /** @private {HTMLElement} */
   this.detailsPanel_ = document.getElementById('cloud-import-details');
   this.detailsPanel_.addEventListener(
       'transitionend',