title: Can't get Popover to display in correct position in Dialog
body: <p>I have a Dialog and have a ListItem that when you click on it goes into edit mode by showing a Popover. This was working in an older version of MUI using a Modal but since getting on the latest that didn't work and I'm trying to use a Popover. I tried to make a simple example on CodeSandox but that works. What happens is the Popover is always in the upper left of the page instead of the ListItem.</p>
  
  <p>I have simplified my code to a simple Button and Popover in the Dialog and still have the same problem and have ran out of ideas on what to try next. The error I get in the console is</p>
  
  <pre><code>[Warning] Material-UI: the `anchorEl` prop provided to the component is invalid.
  The anchor element should be part of the document layout.
  Make sure the element is present in the document or that it's not display none.
  </code></pre>
  
  <p>When the item is clicked I do event.currentTarget just like in the examples and this is what the console.log looks like for it.</p>
  
  <pre><code>[Log] &lt;button class="MuiButtonBase-root MuiButton-root MuiButton-text" tabindex="0" type="button"&gt; (main.chunk.js, line 26437)
  &lt;span class="MuiButton-label"&gt;Click Me&lt;/span&gt;
  &lt;span class="MuiTouchRipple-root"&gt;
  &lt;span class="MuiTouchRipple-ripple MuiTouchRipple-rippleVisible" style="width: 117.2006825918689px; height: 117.2006825918689px; top: -34.60034129593445px; left: -25.60034129593445px;"&gt;
  &lt;span class="MuiTouchRipple-child MuiTouchRipple-childLeaving"&gt;&lt;/span&gt;
  &lt;/span&gt;
  &lt;/span&gt;
  &lt;/button&gt;
  
  </code></pre>
  
  <p>I even tried doing disablePortal in the Dialog which didn't fix it. I also tried using refs which fixed the anchorEl warning but still displays relative to the page and not the element. Any ideas?</p>