Fix all hints discovered by the new linter

`npm run eslintfix`

Change-Id: Ic07aede1b95e7dd53bbd05c062e2afcef5508c10
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-mode-selector/gr-diff-mode-selector.ts b/polygerrit-ui/app/elements/diff/gr-diff-mode-selector/gr-diff-mode-selector.ts
index 6fe9d27..4eb33c7 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-mode-selector/gr-diff-mode-selector.ts
+++ b/polygerrit-ui/app/elements/diff/gr-diff-mode-selector/gr-diff-mode-selector.ts
@@ -51,7 +51,9 @@
   /** @override */
   connectedCallback() {
     super.connectedCallback();
-    ((IronA11yAnnouncer as unknown) as FixIronA11yAnnouncer).requestAvailability();
+    (
+      IronA11yAnnouncer as unknown as FixIronA11yAnnouncer
+    ).requestAvailability();
   }
 
   /**