Return after throwing an exception when ConvolerNode.buffer rate is wrong.

Source/modules/webaudio/ConvolverNode.cpp

Index: Source/modules/webaudio/ConvolverNode.cpp
diff --git a/Source/modules/webaudio/ConvolverNode.cpp b/Source/modules/webaudio/ConvolverNode.cpp
index 191436caba7892466f6035afcf31968ccc9501fb..198b29f33a234cb7100dc3211859791a1a38a08f 100644
--- a/Source/modules/webaudio/ConvolverNode.cpp
+++ b/Source/modules/webaudio/ConvolverNode.cpp
@@ -124,6 +124,7 @@ void ConvolverHandler::setBuffer(AudioBuffer* buffer, ExceptionState& exceptionS
             "The buffer sample rate of " + String::number(buffer->sampleRate())
             + " does not match the context rate of " + String::number(context()->sampleRate())
             + " Hz.");
+        return;
     }
 
     unsigned numberOfChannels = buffer->numberOfChannels();