Fix.

node_modules/cssstyle/lib/properties/fontStyle.js

@@ -1,18 +0,0 @@
-'use strict';
-
-var valid_styles = ['normal', 'italic', 'oblique', 'inherit'];
-
-module.exports.isValid = function(v) {
-  return valid_styles.indexOf(v.toLowerCase()) !== -1;
-};
-
-module.exports.definition = {
-  set: function(v) {
-    this._setProperty('font-style', v);
-  },
-  get: function() {
-    return this.getPropertyValue('font-style');
-  },
-  enumerable: true,
-  configurable: true,
-};