clearCache method
Implementation
@override
Future<void> clearCache() async {
// Outputs are blob: URLs, which the browser keeps alive for the whole page
// unless revoked. Release every URL this engine handed out.
//
// If the engine never loaded it never minted a URL, so there is nothing to
// free — don't fetch the script just to iterate an empty set.
if (!_engineReady) return;
_jsRevokeAll();
}