WIP: Fix lab/lch tests

Author: GPHemsley

Diff for: src/color.rs

@@ -466,7 +466,7 @@ impl ToCss for CielabColor {
                 };
                 dest.write_str(" ")?;
                 match lch_coords.chroma {
-                    Some(chroma) => chroma.to_css(dest)?,
+                    Some(chroma) => chroma.max(0.).to_css(dest)?,
                     None => dest.write_str("none")?,
                 };
                 dest.write_str(" ")?;
@@ -573,7 +573,7 @@ impl ToCss for OklabColor {
                 };
                 dest.write_str(" ")?;
                 match lch_coords.chroma {
-                    Some(chroma) => chroma.to_css(dest)?,
+                    Some(chroma) => chroma.max(0.).to_css(dest)?,
                     None => dest.write_str("none")?,
                 };
                 dest.write_str(" ")?;