Fixed SASS error while processing css

Currently, if you try to include context.js's css in sass, sass processor chokes on IE filter declaration.
```
Syntax error: Invalid CSS after "       filter: progid": expected ";", was ": dximagetransf..."
        on line 79 of **CUT**\app\vendor\contextjs\context.standalone.css
        from line 16 of app/themes/main.scss
```
I cleared this rule a bit, now sass can successfully process this css rule.