Support IE 9 and lower better

Although it is already supported, the problem is that the back-end
expects 2 extra metaframes, if a stack trace was generated by us.

The first approach in `generateStacktrace()` provides these frames,
but if it fails, we fall back to the second approach, which lacks
them. It means that on the back-end side the parser chops off two
important frames.

![screenshot 2014-08-20 21 22 50](https://cloud.githubusercontent.com/assets/1079123/3991809/07092a94-28eb-11e4-873f-524b5ff0efd1.png)

### IE 6
![screenshot 2014-08-20 22 50 26](https://cloud.githubusercontent.com/assets/1079123/3992299/e6fa7b2e-28f7-11e4-88b5-fdf61a69ffc0.png)

### IE 7

![screenshot 2014-08-20 22 49 41](https://cloud.githubusercontent.com/assets/1079123/3992297/e6f318a2-28f7-11e4-9ed2-4842d29e7441.png)

### IE 8 on WinXP

![screenshot 2014-08-20 22 44 40](https://cloud.githubusercontent.com/assets/1079123/3992309/2f5137b4-28f8-11e4-8939-5dcaa94b3659.png)


### IE 8 on Win7

![screenshot 2014-08-20 22 43 45](https://cloud.githubusercontent.com/assets/1079123/3992300/e7175712-28f7-11e4-8592-1ca39569a5d7.png)






Now I can say "yes" ;)