Add more informative messages for DOM exceptions.

Source/modules/webaudio/AnalyserNode.cpp

Index: Source/modules/webaudio/AnalyserNode.cpp
diff --git a/Source/modules/webaudio/AnalyserNode.cpp b/Source/modules/webaudio/AnalyserNode.cpp
index 128840ef9b0e2787c49a12668f9f3992613f2fc4..e8383019ab719c79e6f7178c29562e74e6c27bec 100644
--- a/Source/modules/webaudio/AnalyserNode.cpp
+++ b/Source/modules/webaudio/AnalyserNode.cpp
@@ -28,6 +28,7 @@
 
 #include "modules/webaudio/AnalyserNode.h"
 
+#include "bindings/v8/ExceptionMessages.h"
 #include "bindings/v8/ExceptionState.h"
 #include "core/dom/ExceptionCode.h"
 #include "modules/webaudio/AudioNodeInput.h"
@@ -75,8 +76,17 @@ void AnalyserNode::reset()
 
 void AnalyserNode::setFftSize(unsigned size, ExceptionState& es)
 {
-    if (!m_analyser.setFftSize(size))
-        es.throwUninformativeAndGenericDOMException(NotSupportedError);
+    if (!m_analyser.setFftSize(size)) {
+        es.throwDOMException(
+            NotSupportedError,
+            ExceptionMessages::failedToSet(
+                "fftSize",
+                "AnalyserNode",
+                "FFT size (" + String::number(size)
+                + ") must be a power of two between "
+                + String::number(RealtimeAnalyser::MinFFTSize) + " and "
+                + String::number(RealtimeAnalyser::MaxFFTSize) + ", inclusive"));
+    }
 }
 
 } // namespace WebCore