title: Unable to get a DirectionalLight shadow to update correctly
body: <p>I have a <code>DirectionalLight</code> in my scene. When I first create the light the shadow covers the intended area. When the viewport is resized (canvas size) I update the shadowCamera parameters (right,left,top,bottom), and the light's position and target, but the shadow only covers the area before the update.</p>
  
  <p>What flag do I have to set to get the shadow properly updated to reflect the new settings?</p>