Add override to comply with new noImplicitOverride ts compiler option

Google-Bug-Id: b/201385514
Change-Id: Ie1051f5e63dc71a192da5596691e52d314d5e7e2
diff --git a/web/gr-checkers-list.ts b/web/gr-checkers-list.ts
index c6804bd..2dce3b8 100644
--- a/web/gr-checkers-list.ts
+++ b/web/gr-checkers-list.ts
@@ -90,7 +90,7 @@
     this.loadCheckers();
   }
 
-  static styles = [
+  static override styles = [
     window.Gerrit.styles.table as CSSResult,
     css`
       #container {
diff --git a/web/gr-create-checkers-dialog.ts b/web/gr-create-checkers-dialog.ts
index 1c5aab5..6fd6f14 100644
--- a/web/gr-create-checkers-dialog.ts
+++ b/web/gr-create-checkers-dialog.ts
@@ -100,14 +100,14 @@
     this.initCheckerValues();
   }
 
-  update(changedProperties: PropertyValues) {
+  override update(changedProperties: PropertyValues) {
     if (changedProperties.has('checker')) {
       this.initCheckerValues();
     }
     super.update(changedProperties);
   }
 
-  static styles = [
+  static override styles = [
     window.Gerrit.styles.form as CSSResult,
     css`
       :host {
diff --git a/web/gr-repo-chip.ts b/web/gr-repo-chip.ts
index 6e52701..931f913 100644
--- a/web/gr-repo-chip.ts
+++ b/web/gr-repo-chip.ts
@@ -29,7 +29,7 @@
  */
 @customElement('gr-repo-chip')
 export class GrRepoChip extends LitElement {
-  static styles = css`
+  static override styles = css`
     :host {
       display: inline-block;
     }
@@ -46,7 +46,7 @@
   @property()
   repo = '';
 
-  render() {
+  override render() {
     return html`
       <span>${this.repo}</span>
       <gr-button