Add MS Edge to Autoprefixer config

[skip sauce]
[skip validator]

Gruntfile.js

@@ -231,6 +231,11 @@ module.exports = function (grunt) {
           'Android >= 4',
           'Chrome >= 35',
           'Firefox >= 31',
+          // Note: Edge versions in Autoprefixer & Can I Use refer to the EdgeHTML rendering engine version,
+          // NOT the Edge app version shown in Edge's "About" screen.
+          // For example, at the time of writing, Edge 20 on an up-to-date system uses EdgeHTML 12.
+          // See also https://github.com/Fyrd/caniuse/issues/1928
+          'Edge >= 12',
           'Explorer >= 9',
           'iOS >= 7',
           'Opera >= 12',