Valid regexp breaks minification

The following syntactically correct code breaks the minifier:

```js
var re = /^(([^<>()[\]{}'^?\\.,!|//#%*-+=&;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?/;
```

Internal bracket counts get messed up and code breaks about 2 ( symbols for the end.

The code is valid syntactically.