focusDelegate method doesn't handle custom elements where [autofocus] is in the light DOM (slotted)

[jpzwarte]

The focusDelegate method (

popover-polyfill/src/popover-helpers.ts

Line 188 in 66d6615

function focusDelegate(focusTarget: HTMLElement) {

) checks if the focusTarget has a shadowRoot and if delegatesFocus is enabled.

If it does, it looks for [autofocus] in the shadow root and returns it if found.

It doesn't take the scenario into account where the [autofocus] element is in the light DOM and slotted into the shadow root. focusDelegate will return the shadowRoot itself in that case.

When it is back in the popoverFocusingSteps method it tries to call focus() on the return value, but since shadowRoot does not implement that method, it causes an error (Uncaught TypeError: _a.focus is not a function in FF).