core/platform: Include wtf files using "wtf/foo.h" form.

Source/core/platform/image-encoders/skia/PNGImageEncoder.h

 /*
  * Copyright (c) 2010, Google Inc. All rights reserved.
  * 
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 13 matching lines @@
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef PNGImageEncoder_h
 #define PNGImageEncoder_h
 
-#include <wtf/Vector.h>
+#include "wtf/Vector.h"
 
 class SkBitmap;
 
 namespace WebCore {
 
 class ImageData;
 
 // Interface for encoding PNG data. This is a wrapper around libpng.
 class PNGImageEncoder {
 public:
     static bool encode(const SkBitmap&, Vector<unsigned char>* output);
     static bool encode(const ImageData&, Vector<unsigned char>* output);
 };
 
 } // namespace WebCore
 
 #endif