start/stop method for AudioBufferSourceNodes and OscillatorNodes can take no args.

Source/modules/webaudio/AudioScheduledSourceNode.h

Index: Source/modules/webaudio/AudioScheduledSourceNode.h
diff --git a/Source/modules/webaudio/AudioScheduledSourceNode.h b/Source/modules/webaudio/AudioScheduledSourceNode.h
index f63e72ed07a8977bc65b106e8683b802554426a8..25e4291129f5a69a5ec6cecabaa0c8dd0dce67bc 100644
--- a/Source/modules/webaudio/AudioScheduledSourceNode.h
+++ b/Source/modules/webaudio/AudioScheduledSourceNode.h
@@ -68,8 +68,8 @@ public:
     AudioScheduledSourceNode(AudioContext*, float sampleRate);
 
     // Scheduling.
-    void start(double when);
-    void stop(double when);
+    void start(double when = 0);
+    void stop(double when = 0);
 
     void noteOn(double when);
     void noteOff(double when);