Fix TypeError on `isCSSColorSchemePropSupported`
Fix TypeError on `isCSSColorSchemePropSupported`

- There's a chance that `el.style` can be undefined. We need to account
for that.
- Resolves #8368

alexanderby/darkreader,darkreader/darkreader,darkreader/darkreader,alexanderby/darkreader,alexanderby/darkreader,darkreader/darkreader