What version of CssMin are you using (source and/or build)?
3.0.1

What was the input stylesheet and/or configuration options?
CssAtKeyframesStartToken

What is the expected result?
@keyframe name

And what is the actual result and/or error message?
@keyframe "name"

Please provide any additional information below.
The __toStrig method in CssAtKeyframesStartToken adds " to the name of 
animation. this makes firefox to not see it as valid