Fix typo in comment

Bug: 1014771
Change-Id: Ie8cb8a929d8273faae6f13d31193ed433fc093ab
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1900518
Commit-Queue: Alex Danilo <adanilo@chromium.org>
Commit-Queue: Noel Gordon <noel@chromium.org>
Reviewed-by: Noel Gordon <noel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#712884}

ui/file_manager/file_manager/foreground/elements/files_xf_elements_unittest.js

@@ -134,7 +134,7 @@ async function testDisplayPanelChangingPanelTypes(done) {
   done();
 }
 
-// Override thr formatting function for unit testing.
+// Override the formatting function for unit testing.
 util.strf = (end, option) => {
   return option + end;
 };