Looping AudioBufferSourceNodes stop only if duration is explicitly given.

LayoutTests/webaudio/resources/audiobuffersource-testing.js

 function createTestBuffer(context, sampleFrameLength) {
     var audioBuffer = context.createBuffer(1, sampleFrameLength, context.sampleRate);
     var channelData = audioBuffer.getChannelData(0);
 
     // Create a simple linear ramp starting at zero, with each value in the buffer equal to its index position.
     for (var i = 0; i < sampleFrameLength; ++i)
         channelData[i] = i;
 
     return audioBuffer;
 }
@@ skipping 59 matching lines @@
         testPassed(description);
 
     return success;
 }
 
 function checkAllTests(event) {
     var renderedBuffer = event.renderedBuffer;
     for (var i = 0; i < tests.length; ++i)
         checkSingleTest(renderedBuffer, i);
 
-    if (window.testRunner)
-        testRunner.notifyDone()
+    finishJSTest();
 }