title: Value of document variable inside shadow dom
body: <p>What is the value of <code>document</code> variable inside shadow-dom?
  In <a href="https://jsfiddle.net/36kypL48/2/" rel="nofollow noreferrer">this</a>  jsfiddle we can see that it searches for the <code>app</code> node in the parent document and alerts its value. Does that mean that shadow-dom doesn't have a separate document variable and can access parent's document?</p>