shadow dom is not taken into account in the paint tree

[AutomatedTester]

In chapter 11. Elements, section 11.1 Element Interactability:

An element’s pointer-interactable paint tree is produced this way:

unfortunately elementsFromPoint does not take shadow dom into account, we need to recursively check shadowRoot in case there is one there hidding...

see w3c/csswg-drafts#556 for more context