Adding gradients and minor fixes

Feat @Larry006
I meant I'm pretty sure that GSS will not replace the variable in this following line : 
```CSS
filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='FIRST_COLOR', endColorstr='SECOND_COLOR',GradientType=0 ); /* IE6-9 */
```
because they are surrounded by quotes and they will be considered as a string by GSS.

Moreover, I'm pretty sure that GSS will not accept the function progid:DXImageTransform.Microsoft.gradient(). Because you need explicitly to tell him to accept this not standard function.

Did you try ?