Test that multiple audio elements can play concurrently.

Starting a total of 2 concurrent audio elements.
EVENT(0, canplaythrough)
EXPECTED (0, testElement.currentTime == '0') OK
EVENT(0, playing)
EXPECTED (0, testElement.currentTime > '0') OK
EVENT(1, canplaythrough)
EXPECTED (1, testElement.currentTime == '0') OK
EVENT(1, playing)
EXPECTED (1, testElement.currentTime > '0') OK
Making sure all 2 audio elements are in playing state:
EXPECTED (0, testElement.paused == 'false') OK
EXPECTED (1, testElement.paused == 'false') OK
END OF TEST

