message: Made theme name optional
diff: @@ -136,7 +136,7 @@ export class StylesManager {
  return <CSSStyleSheet>style.sheet;
  }
  - public static applyTheme(themeName: string) {
  + public static applyTheme(themeName?: string) {
  let sheet = StylesManager.findSheet(themeName);
  if (!sheet) {
  sheet = StylesManager.createSheet(themeName);
  