api.ShadowRoot.slotAssignment - `named` value not supported in Chromium 86

What type of issue is this?

Missing compatibility data

What information was incorrect, unhelpful, or incomplete?

In Chromium < 102 the default value of ShadowRoot.slotAssignment is "auto".

What browsers does this problem apply to, if applicable?

Chromium (Chrome, Edge 79+, Opera, Samsung Browser)

What did you expect to see?

Should add an entry like ShadowRoot.slotAssignment defaults to "named".

Did you test this? If so, how?

document.createElement('div').attachShadow({mode: 'open', slotAssignment: 'named'}) throws in Chromium 91.0.4464.0 and not in 92.0.4510.0.

document.createElement('div').attachShadow({mode: 'open'}).slotAssignment and document.createElement('div').attachShadow({mode: 'open', slotAssignment: 'named'}).slotAssignment are "auto" in Chromium 101.0.4949.0 and are "named" in 102.0.4983.0.

Can you link to any release notes, bugs, pull requests, or MDN pages related to this?

No response

Do you have anything more you want to share?

No response

MDN URL

https://developer.mozilla.org/en-US/docs/Web/API/ShadowRoot/slotAssignment

MDN metadata

Start with the ShadowRoot.slotAssignment entry associated with the issue's MDN URL and compare it with the reported Chromium 86–101 and 102 behavior. Update the compatibility data so the default and named-value support reflect those observations, then verify the resulting entry against the issue's documented tests.