[Cleanup] Files.app: Misc style fixes in Javascript code.

chrome/browser/resources/file_manager/js/file_table.js

Index: chrome/browser/resources/file_manager/js/file_table.js
diff --git a/chrome/browser/resources/file_manager/js/file_table.js b/chrome/browser/resources/file_manager/js/file_table.js
index 1c0170b969d601347187cdae4f9147ee6ab91573..225c9d39d084feb3d8c0bec1be5db36e34e314e6 100644
--- a/chrome/browser/resources/file_manager/js/file_table.js
+++ b/chrome/browser/resources/file_manager/js/file_table.js
@@ -553,15 +553,19 @@ filelist.decorateCheckbox = function(input) {
   input.addEventListener('mousedown', stopEventPropagation);
   input.addEventListener('mouseup', stopEventPropagation);
 
-  var self = this;
-  input.addEventListener('click', function(event) {
-    // Revert default action and swallow the event
-    // if this is a multiple click or Shift is pressed.
-    if (event.detail > 1 || event.shiftKey) {
-      this.checked = !this.checked;
-      stopEventPropagation(event);
-    }
-  });
+  input.addEventListener(
+      'click',
+      /**
+       * @this {HTMLInputElement}
+       */
+      function(event) {
+        // Revert default action and swallow the event
+        // if this is a multiple click or Shift is pressed.
+        if (event.detail > 1 || event.shiftKey) {
+          this.checked = !this.checked;
+          stopEventPropagation(event);
+        }
+      });
 };
 
 /**