Apply polyfill to styles in CSS @imports #326
Description
Is your feature request related to how this polyfill works? Please describe.
When fetching styles to be polyfilled, we currently are not following any @import rules. This means that any anchor positioning-related rules in imported stylesheets will not be polyfilled.
Describe the solution you'd like
Before applying the polyfill, we would need to recursively parse all stylesheets for @import rules.
Alternatively, could we use document.stylesheets to do the initial gathering step for us? I'm unsure if imported stylesheets are included, and we'd need to find a solution that works for Shadow documents as well.
Additional context
#324 only addresses part of the issue, by allowing polyfilled stylesheets to import other stylesheets.