Revert contrast() changes in 2.7.1

Author: matthew-dean

lib/less/functions/color.js

@@ -266,41 +266,33 @@ colorFunctions = {
     greyscale: function (color) {
         return colorFunctions.desaturate(color, new Dimension(100));
     },
-    contrast: function (color, color1, color2, threshold) {
-        // Return which of `color1` and `color2` has the greatest contrast with `color`
-        // according to the standard WCAG contrast ratio calculation.
-        // http://www.w3.org/TR/WCAG20/#contrast-ratiodef
-        // The threshold param is no longer used, in line with SASS.
+    contrast: function (color, dark, light, threshold) {
         // filter: contrast(3.2);
         // should be kept as is, so check for color
         if (!color.rgb) {
             return null;
         }
-        if (typeof color1 === 'undefined') {
-            color1 = colorFunctions.rgba(0, 0, 0, 1.0);
+        if (typeof light === 'undefined') {
+            light = colorFunctions.rgba(255, 255, 255, 1.0);
         }
-        if (typeof color2 === 'undefined') {
-            color2 = colorFunctions.rgba(255, 255, 255, 1.0);
+        if (typeof dark === 'undefined') {
+            dark = colorFunctions.rgba(0, 0, 0, 1.0);
         }
-        var contrast1, contrast2;
-        var luma = color.luma();
-        var luma1 = color1.luma();
-        var luma2 = color2.luma();
-        // Calculate contrast ratios for each color
-        if (luma > luma1) {
-            contrast1 = (luma + 0.05) / (luma1 + 0.05);
-        } else {
-            contrast1 = (luma1 + 0.05) / (luma + 0.05);
+        //Figure out which is actually light and dark!
+        if (dark.luma() > light.luma()) {
+            var t = light;
+            light = dark;
+            dark = t;
         }
-        if (luma > luma2) {
-            contrast2 = (luma + 0.05) / (luma2 + 0.05);
+        if (typeof threshold === 'undefined') {
+            threshold = 0.43;
         } else {
-            contrast2 = (luma2 + 0.05) / (luma + 0.05);
+            threshold = number(threshold);
         }
-        if (contrast1 > contrast2) {
-            return color1;
+        if (color.luma() < threshold) {
+            return light;
         } else {
-            return color2;
+            return dark;
         }
     },
     argb: function (color) {

lib/less/index.js

@@ -2,7 +2,7 @@ module.exports = function(environment, fileManagers) {
     var SourceMapOutput, SourceMapBuilder, ParseTree, ImportManager, Environment;
 
     var less = {
-        version: [2, 7, 1],
+        version: [2, 7, 2],
         data: require('./data'),
         tree: require('./tree'),
         Environment: (Environment = require("./environment/environment")),

package.json

@@ -1,6 +1,6 @@
 {
   "name": "less",
-  "version": "2.7.1",
+  "version": "2.7.2",
   "description": "Leaner CSS",
   "homepage": "http://lesscss.org",
   "author": {