Support for Shadow Dom v1 in PIEs

[evaneus]

This is an open question.

As of today: "Chrome 53 (status), Opera 40, and Safari 10 are shipping shadow DOM v1. Edge is under consideration with high priority. Mozilla has an open bug to implement."

Shady Dom and Shady CSS polyfills are available currently.

See: https://developers.google.com/web/fundamentals/getting-started/primers/shadowdom

There are some benefits for encapsulation and possibly theming capabilities through using this within PIEs.

Adding optional support for this to PIE Framework would require that PIE developers can specify that their PIE needs this feature. The PIE player would need to test for the presence of shadow dom or load polyfill.

[evaneus]

See also: https://github.com/Wildhoney/ReactShadow for React support.