Is it possible to build a standalone HTML5 App *without* bundling a browser?
I saw nodekit which is an attempt to use the JavaScript engine already available on each platform.
So for example on Mac it'll probably use WKWebView and on Windows 10 it'll run on the JavaScript Universal apps platform.
For most though, only having to test on electron makes developing apps much simpler and you can have a fully functional app in an installer under 40MB.