Update eslint to v8 (#2196)

Author: marcustyphoon

.eslintrc.yml

@@ -15,9 +15,9 @@
     no-implied-eval: error
     no-mixed-spaces-and-tabs: [error, smart-tabs]
     no-unused-vars:
-     - error
-     - vars: local
-       args: none
+      - error
+      - vars: local
+        args: none
     no-shadow: error
     no-unsafe-negation: error
     no-with: error

Extensions/xkit_patches.js

@@ -3114,6 +3114,8 @@ XKit.extensions.xkit_patches = new Object({
 					$("#xkit_notification_" + m_notification_id).slideDown('slow');
 				}, 100);
 				$("#xkit_notification_" + m_notification_id).click(function() {
+					// TODO: fix this erroneous comparison
+					// eslint-disable-next-line valid-typeof
 					if (typeof callback !== undefined) {
 						try {
 							callback();