title: Angular material 2 autocomplete position wrong
body: <p>I have a problem with autocomplete of material 2.</p>
  
  <p>In my case, I populate the list when the user write down something in the input, but the div(panel) with the options always appear  bellow (If the screen is small I have to scroll down the page). It should appear above the input field when screen is small. </p>
  
  <p>I think the problem is that the position of the panel is only initialised at the beginning when the input is clicked. Anyone can help me with any solution? Is there a way to reset positionY when the list is updated?</p>
  
  <p>Thanks</p>