Tests that MessageEvent.source is correct and can be used for messaging.

On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".


* Sending message 1 to child
* Parent received message 2 from child
PASS messageEvent.source is frames[0]
PASS messageEvent.data is counter + 1
* Sending message 3 to child
* Parent received message 4 from child
PASS messageEvent.source is frames[0]
PASS messageEvent.data is counter + 1
* Sending message 5 to child
* Parent received message 6 from child
PASS messageEvent.source is frames[0]
PASS messageEvent.data is counter + 1
PASS successfullyParsed is true

TEST COMPLETE


--------
Frame: '<!--frame1-->'
--------
* Child received message 1 from parent
PASS messageEvent.source is parent
* Sending message 2 to parent
* Child received message 3 from parent
PASS messageEvent.source is parent
* Sending message 4 to parent
* Child received message 5 from parent
PASS messageEvent.source is parent
* Sending message 6 to parent