Merge pull request #59 from binary1101/master

Server-side rendering bugfix: safeguard against `document` being undefined

Author: Claudéric Demers

src/utils.js

@@ -16,7 +16,7 @@ export const events = {
 };
 
 export const vendorPrefix = (function () {
-    if (typeof window === 'undefined') return ''; // server environment
+    if (typeof window === 'undefined' || typeof document === 'undefined') return ''; // server environment
     let styles = window.getComputedStyle(document.documentElement, '');
     let pre = (Array.prototype.slice
         .call(styles)