Update the current frame count in a safe place

Source/modules/webaudio/ScriptProcessorNode.cpp

Index: Source/modules/webaudio/ScriptProcessorNode.cpp
diff --git a/Source/modules/webaudio/ScriptProcessorNode.cpp b/Source/modules/webaudio/ScriptProcessorNode.cpp
index 7e660aae5bbd7d900e89f468b86b1c4da49a6817..b5d17eac02e754850233545a4a14c2562d66854f 100644
--- a/Source/modules/webaudio/ScriptProcessorNode.cpp
+++ b/Source/modules/webaudio/ScriptProcessorNode.cpp
@@ -259,7 +259,7 @@ void ScriptProcessorNode::fireProcessEvent()
 
         // Calculate a playbackTime with the buffersize which needs to be processed each time onaudioprocess is called.
         // The outputBuffer being passed to JS will be played after exhuasting previous outputBuffer by double-buffering.
-        double playbackTime = (context()->currentSampleFrame() + m_bufferSize) / static_cast<double>(context()->sampleRate());
+        double playbackTime = (context()->cachedSampleFrame() + m_bufferSize) / static_cast<double>(context()->sampleRate());
 
         // Call the JavaScript event handler which will do the audio processing.
         dispatchEvent(AudioProcessingEvent::create(inputBuffer, outputBuffer, playbackTime));