message: Don't try to exit fullscreen if not fullscreen
  This was causing annoying exceptions on latest Chrome. Use
  document.fullScreenElement to detect if we're fullscreen and don't
  try to exit if we aren't.
diff: @@ -26,6 +26,15 @@ import dis from '../../../dispatcher';
  import SettingsStore from "../../../settings/SettingsStore";
  +function getFullScreenElement() {
  + return (
  + document.fullscreenElement ||
  + document.mozFullScreenElement ||
  + document.webkitFullscreenElement ||
  + document.msFullscreenElement
  + );
  +}
  +
  module.exports = React.createClass({
  displayName: 'VideoView',
  @@ -88,7 +97,7 @@ module.exports = React.createClass({
  element.msRequestFullscreen
  );
  requestMethod.call(element);
  - } else {
  + } else if (getFullScreenElement()) {
  const exitMethod = (
  document.exitFullscreen ||
  document.mozCancelFullScreen ||
  @@ -108,10 +117,7 @@ module.exports = React.createClass({
  const VideoFeed = sdk.getComponent('voip.VideoFeed');
  // if we're fullscreen, we don't want to set a maxHeight on the video element.
  - const fullscreenElement = (document.fullscreenElement ||
  - document.mozFullScreenElement ||
  - document.webkitFullscreenElement);
  - const maxVideoHeight = fullscreenElement ? null : this.props.maxHeight;
  + const maxVideoHeight = getFullScreenElement() ? null : this.props.maxHeight;
  const localVideoFeedClasses = classNames("mx_VideoView_localVideoFeed",
  { "mx_VideoView_localVideoFeed_flipped":
  SettingsStore.getValue('VideoView.flipVideoHorizontally'),
  