Don't show hints inside a regexp.

This fixes #10160.
This fix does not work for this case:

```js
    <script>
      function test(x) {
        return (/\.(eot|wo)$/i);
      }
    </script>
```

This is what I'm seeing in debugger:

![hint-in-reqex](https://cloud.githubusercontent.com/assets/1197144/5580546/0b181a14-9001-11e4-8928-d43d60af5b00.png)