Work around css-loader issue during testing

package.json

@@ -30,6 +30,7 @@
   "homepage": "https://github.com/ampedandwired/html-webpack-plugin",
   "devDependencies": {
     "css-loader": "^0.23.0",
+    "es6-promise": "^3.0.2",
     "extract-text-webpack-plugin": "^0.9.1",
     "file-loader": "^0.8.4",
     "jasmine-node": "^1.14.5",

spec/HtmlWebpackPluginSpec.js

@@ -1,4 +1,11 @@
 'use strict';
+
+// Workaround for css-loader issue 
+// https://github.com/webpack/css-loader/issues/144
+if (!global.Promise) {
+  require('es6-promise').polyfill();
+}
+
 var path = require('path');
 var fs = require('fs');
 var webpack = require('webpack');