Fix AudioNode.disconnect() to support selective disconnection.

Source/modules/webaudio/AudioNodeOutput.h

Index: Source/modules/webaudio/AudioNodeOutput.h
diff --git a/Source/modules/webaudio/AudioNodeOutput.h b/Source/modules/webaudio/AudioNodeOutput.h
index 54c0f6fb121f585baacd5205bd34b4ca6dcf6d60..55333b102ae31bdbcb8f79e1faf2564765f953bc 100644
--- a/Source/modules/webaudio/AudioNodeOutput.h
+++ b/Source/modules/webaudio/AudioNodeOutput.h
@@ -66,12 +66,20 @@ public:
     // Must be called with the context's graph lock.
     void disconnectAll();
 
+    // Disconnect a specific input or AudioParam.
+    void disconnectInput(AudioNodeInput &);
+    void disconnectAudioParam(AudioParam &);
+
     void setNumberOfChannels(unsigned);
     unsigned numberOfChannels() const { return m_numberOfChannels; }
     bool isChannelCountKnown() const { return numberOfChannels() > 0; }
 
     bool isConnected() { return fanOutCount() > 0 || paramFanOutCount() > 0; }
 
+    // Probe if the output node is connected with a certain input or AudioParam
+    bool isConnectedWithInput(AudioNodeInput &);
+    bool isConnectedWithAudioParam(AudioParam &);
+
     // Disable/Enable happens when there are still JavaScript references to a node, but it has otherwise "finished" its work.
     // For example, when a note has finished playing.  It is kept around, because it may be played again at a later time.
     // They must be called with the context's graph lock.