Dot before placeholder in template literal breaks css highlighting

[pedroscaff]

Dot before placeholder in template literal breaks css highlighting.

import { css } from 'react-emotion'

const classFoo = 'foo'

const style = css`
  width: 100px;
  // this works
  .foo {
  	width: 100px;
  }
  // this doesn't work
  .${classFoo} {
  	width: 100px;
  }
`