Move late-start-testing.js to only user

third_party/WebKit/LayoutTests/webaudio/resources/late-start-testing.js

-function runLateStartTest(audit, context, node) {
-
-  // Set up a dummy signal path to keep the audio context running and spend
-  // processing time before calling start(0).
-  var osc = context.createOscillator();
-  var silent = context.createGain();
-
-  osc.connect(silent);
-  silent.connect(context.destination);
-  silent.gain.setValueAtTime(0.0, 0);
-  osc.start();
-
-  node.connect(context.destination);
-
-  // Task: schedule a suspend and start rendering.
-  audit.define('test-late-start', (task, should) => {
-    // The node's start time will be clamped to the render quantum boundary
-    // >0.1 sec. Thus the rendered buffer will have non-zero frames.
-    // See issue: crbug.com/462167
-    context.suspend(0.1).then(() => {
-      node.start(0);
-      context.resume();
-    });
-
-    // Start rendering and verify result: this verifies if 1) the rendered
-    // buffer contains at least one non-zero value and 2) the non-zero value is
-    // found later than the first output sample.
-    context.startRendering().then(function (buffer) {
-      var nonZeroValueIndex = -1;
-      var channelData = buffer.getChannelData(0);
-      for (var i = 0; i < channelData.length; i++) {
-        if (channelData[i] !== 0) {
-          nonZeroValueIndex = i;
-          break;
-        }
-      }
-
-      should(nonZeroValueIndex, 'The index of first non-zero value')
-              .notBeEqualTo(-1);
-      should(channelData[0], 'The first sample value')
-          .beEqualTo(0);
-      task.done();
-    });
-  });
-
-  audit.run();
-}