message: Use an AccessibleButton for unpinning from the pane.
diff: @@ -62,8 +62,11 @@ module.exports = React.createClass({
  let unpinButton = null;
  if (this._canUnpin()) {
  - unpinButton = <img src="img/cancel-red.svg" className="mx_PinnedEventTile_unpinButton" width="8" height="8"
  - onClick={this.onUnpinClicked} alt={_t('Unpin Message')} title={_t('Unpin Message')} />;
  + unpinButton = (
  + <AccessibleButton onClick={this.onUnpinClicked} className="mx_PinnedEventTile_unpinButton">
  + <img src="img/cancel-red.svg" width="8" height="8" alt={_t('Unpin Message')} title={_t('Unpin Message')} />
  + </AccessibleButton>
  + );
  }
  return (
  