When trying to call `attachShadow` on a `<main>` element, Safari v12.1 and Safari Technology Preview throw an error: `NotSupportedError: The operation is not supported` even though `<main>` is a valid `attachShadow` target (https://dom.spec.whatwg.org/#dom-element-attachshadow). Test case: https://codepen.io/straker/pen/eapxaw
<rdar://problem/50685550>
Created attachment 380275 [details] Fixes the bug
It's weird that this test never existed. I swear I wrote one and contributed to WPT but I don't see it anymore...
Hm... it looks like I either failed to merge it into WPT or someone else had "refactored" the tests and got rid of my test cases :(
Comment on attachment 380275 [details] Fixes the bug Clearing flags on attachment: 380275 Committed r250770: <https://trac.webkit.org/changeset/250770>
All reviewed patches have been landed. Closing bug.