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

Source/modules/webaudio/AudioBufferSourceNode.h

Index: Source/modules/webaudio/AudioBufferSourceNode.h
diff --git a/Source/modules/webaudio/AudioBufferSourceNode.h b/Source/modules/webaudio/AudioBufferSourceNode.h
index 60bc1be80ef36f8d97cacb64b7d5defac904afe6..021ed4447ea22be1c3d93662a26f7d21f49b05ff 100644
--- a/Source/modules/webaudio/AudioBufferSourceNode.h
+++ b/Source/modules/webaudio/AudioBufferSourceNode.h
@@ -62,8 +62,8 @@ public:
     unsigned numberOfChannels();
 
     // Play-state
-    void startGrain(double when, double grainOffset);
-    void startGrain(double when, double grainOffset, double grainDuration);
+    void start(double when = 0);
+    void start(double when, double grainOffset, double grainDuration = 0);
 
     void noteGrainOn(double when, double grainOffset, double grainDuration);