ShadowRoot.contains doesn't return the right value when passing itself

[pmdartus]

Description

Node.contains should return true if the node passed as parameter is a descendant (ie. itself or a child node). However, when invoking contains on the ShadowRoot and passing itself it returns false instead of true.

const elm = createElement('x-test', { is: Test });
console.log(elm.shadowRoot.contains(elm.shadowRoot));
// Returns: false
// Expected: true

Version

• LWC: 0.35.1