Add constant twoPiDouble/twoPiFloat to MathExtras.h

Source/platform/audio/DynamicsCompressorKernel.cpp

Index: Source/platform/audio/DynamicsCompressorKernel.cpp
diff --git a/Source/platform/audio/DynamicsCompressorKernel.cpp b/Source/platform/audio/DynamicsCompressorKernel.cpp
index 41869b7472eb33f5ccb324ef31e073c2859544ee..1f52859661de80e1ada66d852538d1bde9491785 100644
--- a/Source/platform/audio/DynamicsCompressorKernel.cpp
+++ b/Source/platform/audio/DynamicsCompressorKernel.cpp
@@ -294,7 +294,7 @@ void DynamicsCompressorKernel::process(const float* sourceChannels[],
         float desiredGain = m_detectorAverage;
 
         // Pre-warp so we get desiredGain after sin() warp below.
-        float scaledDesiredGain = asinf(desiredGain) / (0.5f * piFloat);
+        float scaledDesiredGain = asinf(desiredGain) / (piOverTwoFloat);
 
         // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
         // Deal with envelopes
@@ -426,7 +426,7 @@ void DynamicsCompressorKernel::process(const float* sourceChannels[],
                 }
 
                 // Warp pre-compression gain to smooth out sharp exponential transition points.
-                float postWarpCompressorGain = sinf(0.5f * piFloat * compressorGain);
+                float postWarpCompressorGain = sinf(piOverTwoFloat * compressorGain);
 
                 // Calculate total gain using master gain and effect blend.
                 float totalGain = dryMix + wetMix * masterLinearGain * postWarpCompressorGain;