title: StencilJS check if named slot is empty
body: <p>I have a stencilJS component with two named slots. Is there a way to determine if the slots have been assigned values? For instance, the code snippet below show named slots for "<strong>logo</strong>" and "<strong>menu</strong>." How can I check inside the component if both named slots are not empty? Ideally I want to check from inside the component and during componentWillMount() . Thank you. </p>
  
  <pre><code>  &lt;koi-menu breakpoint="768" userToggled="false"&gt;
        &lt;div class="logo__header " slot="logo"&gt;&lt;img src="assets/images/logo.png" /&gt;&lt;/div&gt;
  
        &lt;ul class="nav__wrapper list mw8-ns center-m" slot="menu"&gt;
          &lt;li class="nav__listitem"&gt;&lt;a class="ttu nav__link" href="???"&gt;Why Live Grit&lt;/a&gt;&lt;/li&gt;
          &lt;li class="nav__listitem"&gt;&lt;a class="ttu nav__link" href="???"&gt;Clients&lt;/a&gt;&lt;/li&gt;
          &lt;li class="nav__listitem"&gt;&lt;a class="ttu nav__link" href="???"&gt;Our Programs&lt;/a&gt;&lt;/li&gt;
          &lt;li class="nav__listitem"&gt;&lt;a class="ttu nav__link" href="???"&gt;Our Story&lt;/a&gt;&lt;/li&gt;
        &lt;/ul&gt;
  
    &lt;/koi-menu&gt;
  </code></pre>