Use correct FFT scaling for WebAudio AnalyserNode

Source/modules/webaudio/RealtimeAnalyser.cpp

Index: Source/modules/webaudio/RealtimeAnalyser.cpp
diff --git a/Source/modules/webaudio/RealtimeAnalyser.cpp b/Source/modules/webaudio/RealtimeAnalyser.cpp
index 4d9cb8e9d84c0457e1ca67df617b66fbd2cab4ee..24d7b729cabe902441ddda2c9099e0677199e03f 100644
--- a/Source/modules/webaudio/RealtimeAnalyser.cpp
+++ b/Source/modules/webaudio/RealtimeAnalyser.cpp
@@ -178,7 +178,7 @@ void RealtimeAnalyser::doFFTAnalysis()
     imagP[0] = 0;
 
     // Normalize so than an input sine wave at 0dBfs registers as 0dBfs (undo FFT scaling factor).
-    const double magnitudeScale = 1.0 / DefaultFFTSize;
+    const double magnitudeScale = 1.0 / fftSize;
 
     // A value of 0 does no averaging with the previous result.  Larger values produce slower, but smoother changes.
     double k = m_smoothingTimeConstant;