Tests AudioBufferSourceNode looping with a variety of loop points.

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

PASS loop whole buffer by default with loopStart == loopEnd == 0
PASS loop whole buffer explicitly
PASS loop from middle to end of buffer
PASS loop from start to middle of buffer
PASS loop internally from 4 -> 6
PASS loop internally from 3 -> 7
PASS loop internally from 4 -> 6 with playbackRate of 0.5
PASS loop internally from 4 -> 6 with playbackRate of 1.5
PASS illegal playbackRate of 47 greater than loop length
PASS illegal loop: loopStartFrame > loopEndFrame
PASS illegal loop: loopStartFrame == loopEndFrame
PASS illegal loop: loopStartFrame < 0
PASS illegal loop: loopEndFrame > bufferLength