Minimal support for browser

[guyluz11]

Not having browser support lower this pacage sore.

I am not sure what layout would I expect for action bottom sheet.

Maybe small action sheet from the bottom center that does not take all the page width if it is bigger than x.

[guyluz11]

Did a little digging and found out about universal_io, it is like dart.io but can be used on browser too.

So we can use foundation.dart to detect web if needed and use the universal_io to detect IOS and Android without lowering the package sore.

import 'package:flutter/foundation.dart' show kIsWeb;

if (kIsWeb) {
  // running on the web!
} else {
  // NOT running on the web! You can check for additional platforms here.
}

[guyluz11]

Sharing here testing with browser (code include pull request)

[Daniel-Ioannou]

I am not sure what layout would I expect for web, I am more familiar with mobile app's design guidelines and components. I test your pull request and looks ok for now.

Thank @guyluz11 for your contribution.