As per spec, setAppBadge() should reject with SecurityError if child iframe is not same origin-domain as top-origin. Updated spec change: https://github.com/w3c/badging/pull/107 Relevant test: LayoutTests/imported/w3c/web-platform-tests/badging/setAppBadge_cross_origin.sub.html
<rdar://problem/107109904>
Pull request: https://github.com/WebKit/WebKit/pull/13389