title: Dart, why does using innerHtml to set shadow root content work but appendHtml doesn't?
body: <p>I have made <a href="https://gist.github.com/0xor1/1c2bca65cce3df8ff315" rel="nofollow">this Gist</a> to show the issue but essentially I have found that using <code>shadowRoot.innerHtml = '...'</code> works but using <code>shadowRoot.appendHtml('...')</code> doesn't work, it causes the console warning <code>Removing disallowed element &lt;STYLE&gt;</code> which I can't explain. Anyone know if this is simple the way it is meant to be or is it specific to Dart?</p>