Support all of the CSS color formats

[Joao da Silva]

Properties like canvas.fillStyle can be set to CSS color values:

https://windowjs.org/doc/canvas#canvas.fillStyle

However, a lot of the valid CSS color values aren't supported:

https://developer.mozilla.org/en-US/docs/Web/CSS/color_value

For example: HSL, lab, using system color names, etc.

This should be added to src/css.cc in CSSColorToSkColor.