Update grunt-contrib-cssmin.

Gruntfile.js

@@ -195,7 +195,7 @@ module.exports = function (grunt) {
           keepSpecialComments: '*',
           noAdvanced: true, // turn advanced optimizations off until the issue is fixed in clean-css
           report: 'min',
-          selectorsMergeMode: 'ie8'
+          compatibility: 'ie8'
         },
         src: [
           'docs/assets/css/docs.css',

package.json

@@ -34,7 +34,7 @@
     "grunt-contrib-connect": "~0.6.0",
     "grunt-contrib-copy": "~0.5.0",
     "grunt-contrib-csslint": "~0.2.0",
-    "grunt-contrib-cssmin": "~0.7.0",
+    "grunt-contrib-cssmin": "~0.8.0",
     "grunt-contrib-jade": "~0.10.0",
     "grunt-contrib-jshint": "~0.8.0",
     "grunt-contrib-less": "~0.9.0",