Remove support for experimental SerialConnectEvent
Remove support for experimental SerialConnectEvent

Firing a normal Event at the SerialPort object which was connected or
disconnected has been the behavior since Chromium 89.

GoogleChromeLabs/serial-terminal,GoogleChromeLabs/telnet-client,GoogleChromeLabs/serial-terminal,GoogleChromeLabs/telnet-client,GoogleChromeLabs/telnet-client,GoogleChromeLabs/serial-terminal