fix(hslToRgb): correct % for potential negative hue

Due to the Javascript modulo bug
(https://stackoverflow.com/questions/4467539/javascript-modulo-gives-a-negative-result-for-negative-numbers),
any negative value for hue results in a bug where the resulting color will be black. Negative hues
should cycle through to 359, so that functions like `adjustHue()` can provide consistent behavior
for all colors.

fix #437

src/internalHelpers/_hslToRgb.js

@@ -22,9 +22,9 @@ function hslToRgb(
   }
 
   // formular from https://en.wikipedia.org/wiki/HSL_and_HSV
-  const huePrime = hue % 360 / 60
+  const huePrime = (((hue % 360) + 360) % 360) / 60 // Corrected for potential negative hue
   const chroma = (1 - Math.abs(2 * lightness - 1)) * saturation
-  const secondComponent = chroma * (1 - Math.abs(huePrime % 2 - 1))
+  const secondComponent = chroma * (1 - Math.abs((huePrime % 2) - 1))
 
   let red = 0
   let green = 0