Add note about Firefox 63 beta with native shadow (#3)
Add note about Firefox 63 beta with native shadow (#3)

Tested the Firefox 63 and `document.getSelection()` still reports nodes from the inside of shadow trees.
Tracking issue for `getSelection()` on Shadow Root support in Firefox: https://bugzilla.mozilla.org/show_bug.cgi?id=1430308
GoogleChromeLabs/shadow-selection-polyfill,GoogleChromeLabs/shadow-selection-polyfill