This method has no parameters.
This method does not return a value.
This method releases the MessagePort from its corresponding MessagePort. After calling the close method, message events will no longer be received on this port and postMessage will no longer post any messages. To continue messaging, you need to create a new MessageChannel and resend one of the ports to the other window or document.
For more info, see MessageChannel for a working messaging demo.
Build date: 11/17/2013