chore: Fix linter issues, b=no-bug, c=folders, glance

src/zen/folders/ZenFolders.mjs

@@ -1309,7 +1309,7 @@
       animations.push(
         ...this.#createAnimation(
           itemsToHide,
-          { opacity: 0, height: 0 },
+          { opacity: [1, 0], height: ['auto', 0] },
           { duration: 0.12, ease: 'easeInOut' }
         ),
         ...this.updateFolderIcon(group),

src/zen/glance/ZenGlanceManager.mjs

@@ -315,6 +315,10 @@
      * @returns {Promise<Tab>} Promise that resolves to the glance tab
      */
     #animateGlanceOpening(data, browserElement) {
+      // FIXME(cheffy): We *must* have the call back async (at least,
+      // until a better solution is found). If we do it inside the requestAnimationFrame,
+      // we see flashing and if we do it directly, the animation does not play at all.
+      // eslint-disable-next-line no-async-promise-executor
       return new Promise(async (resolve) => {
         this.#prepareGlanceAnimation(data, browserElement);
         if (data.width && data.height) {

src/zen/urlbar/ZenSiteDataPanel.sys.mjs

@@ -82,7 +82,7 @@ export class nsZenSiteDataPanel {
     container.appendChild(fragment);
 
     const aElement = this.document.getElementById('zen-copy-url-button');
-    aElement.addEventListener('click', (event) => {
+    aElement.addEventListener('click', () => {
       this.document.getElementById('cmd_zenCopyCurrentURL').doCommand();
     });