Fix virtual/override/final usage in Source/platform/.

Source/platform/exported/WebMediaStreamSource.cpp

Index: Source/platform/exported/WebMediaStreamSource.cpp
diff --git a/Source/platform/exported/WebMediaStreamSource.cpp b/Source/platform/exported/WebMediaStreamSource.cpp
index b130dd87065e3c87eefdd053e09ac4ed7bd14e40..3e0db826cb568ef3b033a134366f8bc2e0065c50 100644
--- a/Source/platform/exported/WebMediaStreamSource.cpp
+++ b/Source/platform/exported/WebMediaStreamSource.cpp
@@ -178,8 +178,8 @@ public:
         return new ConsumerWrapper(consumer);
     }
 
-    virtual void setFormat(size_t numberOfChannels, float sampleRate) override;
-    virtual void consumeAudio(AudioBus*, size_t numberOfFrames) override;
+    void setFormat(size_t numberOfChannels, float sampleRate) override;
+    void consumeAudio(AudioBus*, size_t numberOfFrames) override;
 
     WebAudioDestinationConsumer* consumer() { return m_consumer; }