Dont' override glamor methods, use a new object instead (#754)

Author: timneutkens

lib/css.js

@@ -1,5 +1,7 @@
 import { deprecated } from './utils'
-const css = require('glamor')
+import glamor from 'glamor'
+
+const css = Object.assign({}, glamor)
 
 for (const [k, v] of Object.entries(css)) {
   if (typeof v === 'function') {