support browser environment

[LennieLT]

hi，i found some node_modules use @wry, and when i use these modules in browser environment, i can't transform some ES6 apis elegant，would you mind support it using some babel plugins in your modules, or you can tell me how to fix the problem, thanks!

[ScottAwesome]

@benjamn this would be a simple thing to do with the rollup config to have it target ES5 as a secondary output. I could make such an update if you're open to it