The addition of a constructor to the <a data-l10n-name="mdn-cssstylesheet">CSSStyleSheet</a> interface as well as a variety of related changes makes it possible to directly create new stylesheets without having to add the sheet to the HTML. This makes it much easier to create reusable stylesheets for use with <a data-l10n-name="mdn-shadowdom">Shadow DOM</a>. See <a data-l10n-name="bugzilla">bug 1520690</a> for more details.
The addition of a constructor to the <a data-l10n-name="mdn-cssstylesheet">CSSStyleSheet</a> interface as well as a variety of related changes makes it possible to directly create new stylesheets without having to add the sheet to the HTML. This makes it much easier to create reusable stylesheets for use with <a data-l10n-name="mdn-shadowdom">Shadow DOM</a>. See <a data-l10n-name="bugzilla">bug 1520690</a> for more details.