feat(vaadin-select): warn when using legacy Template API

Author: vursen

packages/vaadin-select/src/vaadin-select.js

@@ -10,6 +10,7 @@ import { ControlStateMixin } from '@vaadin/vaadin-control-state-mixin/vaadin-con
 import { IronResizableBehavior } from '@polymer/iron-resizable-behavior/iron-resizable-behavior.js';
 import '@polymer/iron-media-query/iron-media-query.js';
 import { ElementMixin } from '@vaadin/vaadin-element-mixin/vaadin-element-mixin.js';
+import { TemplateRendererMixin } from '@vaadin/vaadin-element-mixin/vaadin-template-renderer-mixin.js';
 import './vaadin-select-overlay.js';
 import './vaadin-select-text-field.js';
 const $_documentContainer = document.createElement('template');
@@ -113,8 +114,8 @@ document.head.appendChild($_documentContainer.content);
  * @mixes ControlStateMixin
  * @mixes ThemableMixin
  */
-class SelectElement extends ElementMixin(
-  ControlStateMixin(ThemableMixin(mixinBehaviors(IronResizableBehavior, PolymerElement)))
+class SelectElement extends TemplateRendererMixin(
+  ElementMixin(ControlStateMixin(ThemableMixin(mixinBehaviors(IronResizableBehavior, PolymerElement))))
 ) {
   static get template() {
     return html`
@@ -359,10 +360,6 @@ class SelectElement extends ElementMixin(
 
     this.focusElement.addEventListener('click', () => (this.opened = !this.readonly));
     this.focusElement.addEventListener('keydown', (e) => this._onKeyDown(e));
-
-    if (window.Vaadin && window.Vaadin.templateRendererCallback) {
-      window.Vaadin.templateRendererCallback(this);
-    }
   }
 
   /**