Drop outdated "Issue 1" from spec

This issue was originally added in commit
931b46e in 2017. The referenced discussion
seems to have stalled shortly thereafter, so this issue is most likely no longer
relevant.

index.bs

@@ -3991,10 +3991,6 @@ should continue. When the {{Window}} object associated with the [=Document=] los
 {{PublicKeyCredential/[CREATE-METHOD]}} and {{PublicKeyCredential/[DISCOVER-METHOD]}} operations
 SHOULD be aborted.
 
-    Issue: The WHATWG HTML WG is discussing whether to provide a hook when a browsing context gains or
-    loses focuses. If a hook is provided, the above paragraph will be updated to include the hook.
-    See [WHATWG HTML WG Issue #2711](https://github.com/whatwg/html/issues/2711) for more details.
-
 
 ## WebAuthn Extensions Inputs and Outputs ## {#sctn-extensions-inputs-outputs}