Access current frame counter carefully and remove m_cachedSampleFrame.

Source/modules/webaudio/AudioDestinationNode.cpp

Index: Source/modules/webaudio/AudioDestinationNode.cpp
diff --git a/Source/modules/webaudio/AudioDestinationNode.cpp b/Source/modules/webaudio/AudioDestinationNode.cpp
index 538a366a9c16e6424baac2ee29d0c6c9190e4e4e..920bb6cef15abd48fa14f9edccea93b494906984 100644
--- a/Source/modules/webaudio/AudioDestinationNode.cpp
+++ b/Source/modules/webaudio/AudioDestinationNode.cpp
@@ -31,6 +31,7 @@
 #include "modules/webaudio/AudioNodeOutput.h"
 #include "platform/audio/AudioUtilities.h"
 #include "platform/audio/DenormalDisabler.h"
+#include "wtf/Atomics.h"
 
 namespace blink {
 
@@ -90,7 +91,8 @@ void AudioDestinationHandler::render(AudioBus* sourceBus, AudioBus* destinationB
     context()->handlePostRenderTasks();
 
     // Advance current sample-frame.
-    m_currentSampleFrame += numberOfFrames;
+    size_t newSampleFrame = m_currentSampleFrame + numberOfFrames;
+    releaseStore(&m_currentSampleFrame, newSampleFrame);
 }
 
 // ----------------------------------------------------------------