Get rid of custom bindings for AudioBufferSourceNode.buffer setter

Source/modules/webaudio/AudioBufferSourceNode.cpp

Index: Source/modules/webaudio/AudioBufferSourceNode.cpp
diff --git a/Source/modules/webaudio/AudioBufferSourceNode.cpp b/Source/modules/webaudio/AudioBufferSourceNode.cpp
index 19aa3e6816aa3fe60e7acc8903a4862976a52c31..e5a4791d8250a8e8f88f87be7e75210b4a83110a 100644
--- a/Source/modules/webaudio/AudioBufferSourceNode.cpp
+++ b/Source/modules/webaudio/AudioBufferSourceNode.cpp
@@ -28,6 +28,7 @@
 
 #include "modules/webaudio/AudioBufferSourceNode.h"
 
+#include "bindings/v8/ExceptionState.h"
 #include "core/page/PageConsole.h"
 #include "platform/audio/AudioUtilities.h"
 #include "modules/webaudio/AudioContext.h"
@@ -335,9 +336,15 @@ void AudioBufferSourceNode::reset()
     m_lastGain = gain()->value();
 }
 
-bool AudioBufferSourceNode::setBuffer(AudioBuffer* buffer)
+void AudioBufferSourceNode::setBuffer(AudioBuffer* buffer, ExceptionState& es)
 {
     ASSERT(isMainThread());
+    // FIXME: It does not look like we should throw if the buffer is null as
+    // the attribute is nullable in the specification.
+    if (!buffer) {
+        es.throwTypeError("buffer cannot be null");
+        return;
+    }
 
     // The context must be locked since changing the buffer can re-configure the number of channels that are output.
     AudioContext::AutoLocker contextLocker(context());
@@ -349,8 +356,10 @@ bool AudioBufferSourceNode::setBuffer(AudioBuffer* buffer)
         // Do any necesssary re-configuration to the buffer's number of channels.
         unsigned numberOfChannels = buffer->numberOfChannels();
 
-        if (numberOfChannels > AudioContext::maxNumberOfChannels())
-            return false;
+        if (numberOfChannels > AudioContext::maxNumberOfChannels()) {
+            es.throwTypeError("AudioBuffer unsupported number of channels");

[Raymond Toy (Google), 2013/10/10 22:40:57]

Should this be a DOMException?  And if so, can we have a more informative
message like what was done in https://codereview.chromium.org/24877002/?

+            return;
+        }
 
         output(0)->setNumberOfChannels(numberOfChannels);
 
@@ -363,8 +372,6 @@ bool AudioBufferSourceNode::setBuffer(AudioBuffer* buffer)
 
     m_virtualReadIndex = 0;
     m_buffer = buffer;
-
-    return true;
 }
 
 unsigned AudioBufferSourceNode::numberOfChannels()