JavaScript : \ in templates strings are incorrectly highlighted

```js
`something with \ this`;  // '\' is highlighted as error
`something with \n this`;  // same
`something with \b this`;  // same
`something with \etc this`;  // same
```
Same problem with JavaScript variants (TypeScript for example).
Example : https://pygments.org/demo/?lexer=js&code=%60this%5Cndoesn't%5Cnwork%60%3B.