Files.app: Fix a visibility issue of delete button.

ui/file_manager/file_manager/foreground/css/file_manager.css

Index: ui/file_manager/file_manager/foreground/css/file_manager.css
diff --git a/ui/file_manager/file_manager/foreground/css/file_manager.css b/ui/file_manager/file_manager/foreground/css/file_manager.css
index aa00bd1b4dd9b6b75bf1eade36f313f938725af6..fcb7f427830f555c34b9f8c70e9c5165146580ec 100644
--- a/ui/file_manager/file_manager/foreground/css/file_manager.css
+++ b/ui/file_manager/file_manager/foreground/css/file_manager.css
@@ -399,7 +399,7 @@ body.check-select #share-button > .icon {
       url(../images/files/ui/2x/delete_white.png) 2x);
 }
 
-body.check-select #delete-button {
+body.check-select #delete-button > .icon {
   background-image: -webkit-image-set(
       url(../images/files/ui/delete.png) 1x,
       url(../images/files/ui/2x/delete.png) 2x);