message: Simplify getClassName function
diff: import { OS, platform } from '../lib/platform';
  -import classNames from '../lib/classNames';
  export default function getClassname(base: string, osname: OS = platform()): string {
  - return classNames(base, {
  - [base + '--ios']: osname === OS.IOS,
  - [base + '--android']: osname === OS.ANDROID,
  - });
  + return `${base} ${base}--${osname}`;
  }
  