typo remove method

[youkinjoh]

This logic is remove method when reconnect.

Target method name is onclose .

    connection.onclose = _ => {
      connection = null;
      showDisconnectedUI();
    };

But, this logic remove onclosed method.

    // Disconnect from existing presentation, if not attempting to reconnect
    if (connection && connection != newConnection && connection.state != 'closed') {
      connection.onclosed = undefined;
      connection.close();
    }

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[w3cbot]

tidoust marked as non substantive for IPR from ash-nazg.

[anssiko]

@youkinjoh thank you for your attention to detail!

[anssiko]

(It looks like the CI failure is unrelated, trying to merge.)