message: make icon optional in action button
  as we'll draw the icon with css
diff: @@ -30,7 +30,7 @@ export default React.createClass({
  action: PropTypes.string.isRequired,
  mouseOverAction: PropTypes.string,
  label: PropTypes.string.isRequired,
  - iconPath: PropTypes.string.isRequired,
  + iconPath: PropTypes.string,
  },
  getDefaultProps: function() {
  @@ -72,6 +72,10 @@ export default React.createClass({
  tooltip = <RoomTooltip className="mx_RoleButton_tooltip" label={this.props.label} />;
  }
  + const icon = this.props.iconPath ?
  + (<TintableSvg src={this.props.iconPath} width={this.props.size} height={this.props.size} />) :
  + undefined;
  +
  return (
  <AccessibleButton className="mx_RoleButton"
  onClick={this._onClick}
  @@ -79,7 +83,7 @@ export default React.createClass({
  onMouseLeave={this._onMouseLeave}
  aria-label={this.props.label}
  >
  - <TintableSvg src={this.props.iconPath} width={this.props.size} height={this.props.size} />
  + { icon }
  { tooltip }
  </AccessibleButton>
  );
  