Fix AudioNode.disconnect() to support selective disconnection.

Source/modules/webaudio/AudioNodeOutput.cpp

Index: Source/modules/webaudio/AudioNodeOutput.cpp
diff --git a/Source/modules/webaudio/AudioNodeOutput.cpp b/Source/modules/webaudio/AudioNodeOutput.cpp
index d1fd4a1aee0fd3a1cd0b2520e9348a6d723838c4..0c364c1f81a59ab8d269672e713b94b7d0ec32bc 100644
--- a/Source/modules/webaudio/AudioNodeOutput.cpp
+++ b/Source/modules/webaudio/AudioNodeOutput.cpp
@@ -190,6 +190,18 @@ void AudioNodeOutput::disconnectAllInputs()
         m_inputs.begin()->key->disconnect(*this);
 }
 
+void AudioNodeOutput::disconnectInput(AudioNodeInput& input)
+{
+    ASSERT(context()->isGraphOwner() && isConnectedWithInput(input));
+    input.disconnect(*this);
+}
+
+void AudioNodeOutput::disconnectAudioParam(AudioParam& param)
+{
+    ASSERT(context()->isGraphOwner() && isConnectedWithAudioParam(param));
+    param.disconnect(*this);
+}
+
 void AudioNodeOutput::addParam(AudioParam& param)
 {
     ASSERT(context()->isGraphOwner());
@@ -217,6 +229,18 @@ void AudioNodeOutput::disconnectAll()
     disconnectAllParams();
 }
 
+bool AudioNodeOutput::isConnectedWithInput(AudioNodeInput& input)

[Raymond Toy, 2015/02/11 21:31:18]

ConnectedWithInput or ConnectedToInput? I think the latter reads better.  Same
with AudioParam below.

[hongchan, 2015/02/12 18:38:01]

Done.

+{
+    ASSERT(context()->isGraphOwner());
+    return m_inputs.contains(&input);
+}
+
+bool AudioNodeOutput::isConnectedWithAudioParam(AudioParam& param)
+{
+    ASSERT(context()->isGraphOwner());
+    return m_params.contains(&param);
+}
+
 void AudioNodeOutput::disable()
 {
     ASSERT(context()->isGraphOwner());