[add] default option for Platform.select

See: f30ab35e92

src/apis/Platform/index.js

@@ -1,6 +1,6 @@
 const Platform = {
   OS: 'web',
-  select: (obj: Object) => obj.web
+  select: (obj: Object) => 'web' in obj ? obj.web : obj.default
 };
 
 module.exports = Platform;