Implement "sepia" css filter function
Suddenly reappearing to address #717 (closed).
Two changes:
Add a NumberOrPercentage
struct which implements Parse
. Many of the filter functions use this argument type. There's a cssparser::NumberOrPercentage
but for the life of me I couldn't figure out how to get at it. It's possible we could replace this implementation with that one.
And then add the sepia filter, which is a basic ColorMatrix.