fix: compat SSR (#51)

* fix ssr

* Update dom.js

Author: shiyiya

src/engine/dom.js

@@ -1,4 +1,6 @@
 var transform = (function() {
+  /* istanbul ignore next */
+  if (typeof document === 'undefined') return 'transform';
   var properties = [
     'oTransform', // Opera 11.5
     'msTransform', // IE 9