Fix stylelint error message timer

edit/edit.js

@@ -1902,7 +1902,9 @@ function showHelp(title, body) {
       ((e.keyCode || e.which) === 27 && !e.altKey && !e.ctrlKey && !e.shiftKey && !e.metaKey)
     ) {
       div.style.display = '';
-      document.querySelector('.contents').textContent = '';
+      const contents = $('.contents');
+      contents.textContent = '';
+      clearTimeout(contents.timer);
       document.removeEventListener('keydown', closeHelp);
     }
   }

edit/lint.js

@@ -216,7 +216,6 @@ function showLintHelp() {
 }
 
 function setupStylelintSettingsEvents(popup) {
-  let timer;
   popup.querySelector('.save').addEventListener('click', event => {
     event.preventDefault();
     const json = tryJSONparse(popup.codebox.getValue());
@@ -228,8 +227,8 @@ function setupStylelintSettingsEvents(popup) {
       }
     } else {
       $('#help-popup .error').classList.add('show');
-      clearTimeout(timer);
-      timer = setTimeout(() => {
+      clearTimeout($('#help-popup .contents').timer);
+      $('#help-popup .contents').timer = setTimeout(() => {
         // popup may be closed at this point
         const error = $('#help-popup .error');
         if (error) {
@@ -267,7 +266,6 @@ function setupStylelintPopup(rules) {
     cm.setOption('lint', 'json');
   }
   const popup = showCodeMirrorPopup(t('setStylelintRules'), $element({
-    className: 'contents',
     appendChild: [
       $element({
         tag: 'p',