Current implementation of InsertionPoint::isActive() returns 'true' even if the insertion point is not inside of Shadow DOM subtree. The spec says: > If an insertion point is not in a shadow DOM subtree, it must have the same rendering behavior as the HTMLUnknownElement. So we should return false for such an insertion point to avoid confusion.
https://bugs.webkit.org/show_bug.cgi?id=86829 will fix this issue.
https://bugs.webkit.org/show_bug.cgi?id=86830 fixed this.