Remove unused 'hidden' test on panel items

No change in behaviour, just tidy up removal of a test for the
hidden attribute on a panel item which is never set.

Bug: 980452
Change-Id: I61d32291448132434c77a0df5f5d84ee9cae4cd2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1873813
Commit-Queue: Alex Danilo <adanilo@chromium.org>
Commit-Queue: Luciano Pacheco <lucmult@chromium.org>
Auto-Submit: Alex Danilo <adanilo@chromium.org>
Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Cr-Commit-Position: refs/heads/master@{#708432}

ui/file_manager/file_manager/foreground/js/ui/progress_center_panel.js

@@ -441,8 +441,7 @@ class ProgressCenterPanel {
         case 'completed':
           // Create a completed panel for copies and moves.
           // TODO(crbug.com/947388) decide if we want these for delete, etc.
-          if (panelItem.hidden === false &&
-              (item.type === 'copy' || item.type === 'move')) {
+          if (item.type === 'copy' || item.type === 'move') {
             const donePanelItem = this.completedHost_.addPanelItem(item.id);
             donePanelItem.panelType = donePanelItem.panelTypeDone;
             donePanelItem.primaryText =