Update color.js and run benchmark

# dom/get-computed-style/getComputedStyle() on document.body #
jsdom  x 28,467 ops/sec ±1.05% (89 runs sampled)

# dom/get-computed-style/getComputedStyle() on element with non-rgb color #
jsdom  x 29,178 ops/sec ±0.91% (91 runs sampled)

# dom/get-computed-style/getComputedStyle() on element with rgb color #
jsdom  x 13,822 ops/sec ±2.08% (84 runs sampled)

lib/jsdom/living/helpers/colors.js

@@ -1,5 +1,7 @@
 "use strict";
 
+const { resolve: getResolvedValueForColor } = require("@asamuzakjp/css-color");
+
 // https://drafts.csswg.org/css-color-4/#named-color
 const namedColors = {
   __proto__: null,
@@ -193,11 +195,11 @@ function sharedSpecifiedAndComputedAndUsed(color) {
     return hexToRGBA(color.slice(1));
   }
 
-  if (/^rgba?\(/.test(color)) {
+  if (/^rgba?\(/.test(color) && color.includes(",")) {
     return color.split(",").map(s => s.trim()).join(", ");
   }
 
-  return color;
+  return getResolvedValueForColor(color);
 }
 
 function hexToRGB(color) {