Pick a random port for the firefox cdp implementation to listen on
@@ -193,6 +193,7 @@ protected File findDefaultExecutable() {
protected List<String> createArgs() {
List<String> args = new ArrayList<>();
args.add(String.format("--port=%d", getPort()));
+ args.add(String.format("--websocket-port=%d", PortProber.findFreePort()));
if (firefoxBinary != null) {
args.add("-b");
args.add(firefoxBinary.getPath());
