Correct ariaChecked usage in ElementInternals example

Author: annevk

source

@@ -69039,14 +69039,14 @@ customElements.define('my-checkbox', MyCheckbox);</code></pre>
     this.addEventListener('click', this._onClick.bind(this));
 
 <mark>    this._internals.role = 'checkbox';
-    this._internals.ariaChecked = false;</mark>
+    this._internals.ariaChecked = 'false';</mark>
   }
 
   get form() { return this._internals.form; }
   get name() { return this.getAttribute('name'); }
   get type() { return this.localName; }
 
-  get checked() { return this.getAttribute('checked'); }
+  get checked() { return this.hasAttribute('checked'); }
   set checked(flag) { this.toggleAttribute('checked', Boolean(flag)); }
 
   attributeChangedCallback(name, oldValue, newValue) {