e2ac38c2a8
In bug 1967507 I changed the timing of AnonymousContent stylesheet loading in a way that it perturbed a css cache test because of accessiblecaret.css https://hg.mozilla.org/mozilla-central/rev/a6a294ae1d18 However that made me realize that accessiblecaret.css is loaded virtually in all processes, and it should be using the same mechanism we use for UA sheets, rather than using all the CSS loader machinery in-content. Same goes for details.css. Expand GlobalStyleSheetCache to allow UA and Author sheets, and allow ShadowRoot to get built-in stylesheets appended. This allows accessiblecaret.css and details.css not to be marked as content-accessible. We could do the same at the document level for plaintext.css and co, but that seems a bit less common, so maybe fine. Differential Revision: https://phabricator.services.mozilla.com/D250909