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

Source/platform/image-decoders/bmp/BMPImageDecoder.h

Index: Source/platform/image-decoders/bmp/BMPImageDecoder.h
diff --git a/Source/platform/image-decoders/bmp/BMPImageDecoder.h b/Source/platform/image-decoders/bmp/BMPImageDecoder.h
index 04acab0f46687a2bc577a25add726a2e43cb6c3f..494b2a2ce8d8e78f754e49654eb996c32cbff306 100644
--- a/Source/platform/image-decoders/bmp/BMPImageDecoder.h
+++ b/Source/platform/image-decoders/bmp/BMPImageDecoder.h
@@ -42,17 +42,17 @@ public:
     BMPImageDecoder(ImageSource::AlphaOption, ImageSource::GammaAndColorProfileOption, size_t maxDecodedBytes);
 
     // ImageDecoder:
-    virtual String filenameExtension() const override { return "bmp"; }
-    virtual void setData(SharedBuffer*, bool allDataReceived) override;
+    String filenameExtension() const override { return "bmp"; }
+    void setData(SharedBuffer*, bool allDataReceived) override;
     // CAUTION: setFailed() deletes |m_reader|.  Be careful to avoid
     // accessing deleted memory, especially when calling this from inside
     // BMPImageReader!
-    virtual bool setFailed() override;
+    bool setFailed() override;
 
 private:
     // ImageDecoder:
-    virtual void decodeSize() override { decode(true); }
-    virtual void decode(size_t) override { decode(false); }
+    void decodeSize() override { decode(true); }
+    void decode(size_t) override { decode(false); }
 
     inline uint32_t readUint32(int offset) const
     {