Remove cache feature to remove indirection

It doesn't work reliably and the double refresh adds another indirection layer, which can cause confusion. Also the parsing isn't very time consuming in my measurements.

This was the error I was getting using the caching feature in Firefox 24 on OSX:
```
[16:43:20.040] NS_ERROR_FILE_CORRUPTED: Component returned failure code: 0x8052000b 
(NS_ERROR_FILE_CORRUPTED) [nsIDOMStorage.getItem] 
@ http://example.org/v5b33fae/core/js/compat/css-filters.js:13
```