HTTP request headers not modified for frames

Webug 1.3.1 does only modify the HTTP request headers of the main page, not for the frames within that page.

Main page headers:

```
X-FirePHP:0.4.4
X-FirePHP-Version:0.4.4
X-Wf-Max-Combined-Size:262144
```

The frame pages do not have that request headers.

This makes it impossible to debug the TYPO3 CMS backend.

Test URL: http://p.cweiske.de/196/raw/index.htm
