resolve react-dom/server (#688)

Author: nkzawa

server/build/babel/preset.js

@@ -20,6 +20,7 @@ module.exports = {
           'babel-runtime': babelRuntimePath,
           react: require.resolve('react'),
           'react-dom': require.resolve('react-dom'),
+          'react-dom/server': require.resolve('react-dom/server'),
           'next/link': require.resolve('../../../lib/link'),
           'next/prefetch': require.resolve('../../../lib/prefetch'),
           'next/css': require.resolve('../../../lib/css'),