BREAKING CHANGE: `createApp` API has been adjusted.
  - `createApp()` now accepts the root component, and optionally a props
  object to pass to the root component.
  - `app.mount()` now accepts a single argument (the root container)
  - `app.unmount()` no longer requires arguments.
  New behavior looks like the following:
  ``` js
  const app = createApp(RootComponent)
  app.mount('#app')
  app.unmount()
  ```
		
	
@vue/runtime-test
import { h, render, nodeOps, dumpOps } from '@vue/runtime-test'
const App = {
  data () {
    return {
      msg: 'Hello World!'
    }
  }
  render () {
    return h('div', this.msg)
  }
}
// root is of type `TestElement` as defined in src/nodeOps.ts
const root = nodeOps.createElement('div')
render(h(App), root)
const ops = dumpOps()
console.log(ops)