Unexpected `.replace` behavior

```js
> new (require('magic-string'))('foo+bar').replace('foo\\.bar', 'replaced').toString()
'foo+bar'
> new (require('magic-string'))('foo+bar').replace('foo.bar', 'replaced').toString()
'replaced'
```

This behavior is unexpected to me. Why don't we use `String#indexOf` instead of `String#match`?