Update css-color-function to enable contrast()

Author: vanwagonet

README.md

@@ -67,7 +67,7 @@ color( [ <color> | <hue> ] <color-adjuster>* )
 - `shade( <percentage> )`
 - `blend( <color> <percentage> [rgb | hsl | hwb]? )`
 - ~~`blenda( <color> <percentage> [rgb | hsl | hwb]? )`~~ @todo
-- ~~`contrast( <percentage>? )`~~ @todo
+- `contrast( <percentage>? )`
 
 Notes:
 

package.json

@@ -23,7 +23,7 @@
   ],
   "dependencies": {
     "balanced-match": "^0.1.0",
-    "css-color-function": "^1.1.1",
+    "css-color-function": "^1.2.0",
     "postcss-message-helpers": "^1.1.0"
   },
   "devDependencies": {

test/fixtures/color.css

@@ -2,4 +2,5 @@ body {
   color: color(red);
   background-color: color(red tint(50%));
   border-color: color(hsla(125, 50%, 50%, .4) hue(200));
+  border-top-color: color(hwb(270, 10%, 0%) contrast(50%));
 }

test/fixtures/color.expected.css

@@ -2,4 +2,5 @@ body {
   color: rgb(255, 0, 0);
   background-color: rgb(255, 128, 128);
   border-color: rgba(64, 149, 191, 0.4);
+  border-top-color: rgb(248, 240, 255);
 }