Implement IIRFilter node for WebAudio.

third_party/WebKit/Source/modules/webaudio/AudioNode.cpp

Index: third_party/WebKit/Source/modules/webaudio/AudioNode.cpp
diff --git a/third_party/WebKit/Source/modules/webaudio/AudioNode.cpp b/third_party/WebKit/Source/modules/webaudio/AudioNode.cpp
index 4b3722731bd33d91e596f822c4906fd686475b49..099e457ff9007575264a2b32c875d2258c00c8cf 100644
--- a/third_party/WebKit/Source/modules/webaudio/AudioNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/AudioNode.cpp
@@ -412,14 +412,15 @@ void AudioHandler::disableOutputsIfNecessary()
         // But internally our outputs should be disabled from the inputs they're connected to.
         // disable() can recursively deref connections (and call disable()) down a whole chain of connected nodes.
 
-        // TODO(rtoy,hongchan): we special case the convolver, delay, and biquad since they have a
-        // significant tail-time and shouldn't be disconnected simply because they no longer have
-        // any input connections. This needs to be handled more generally where AudioNodes have a
-        // tailTime attribute. Then the AudioNode only needs to remain "active" for tailTime seconds
-        // after there are no longer any active connections.
+        // TODO(rtoy,hongchan): we need special cases the convolver, delay, biquad, and IIR since
+        // they have a significant tail-time and shouldn't be disconnected simply because they no
+        // longer have any input connections. This needs to be handled more generally where
+        // AudioNodes have a tailTime attribute. Then the AudioNode only needs to remain "active"
+        // for tailTime seconds after there are no longer any active connections.
         if (nodeType() != NodeTypeConvolver
             && nodeType() != NodeTypeDelay
-            && nodeType() != NodeTypeBiquadFilter) {
+            && nodeType() != NodeTypeBiquadFilter
+            && nodeType() != NodeTypeIIRFilter) {
             m_isDisabled = true;
             clearInternalStateWhenDisabled();
             for (auto& output : m_outputs)