Remove some unnecessary #includes of SkImageFilter.h

src/core/SkSpecialImage.h

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file
  */
 
 #ifndef SkSpecialImage_DEFINED
 #define SkSpecialImage_DEFINED
 
 #include "SkNextID.h"
 #include "SkRefCnt.h"
 #include "SkSurfaceProps.h"
 
-// remove this when internal_getProxy goes away (see skbug.com/4965)
-#include "SkImageFilter.h"
-
 #include "SkImageInfo.h" // for SkAlphaType
 
 class GrContext;
 class GrTexture;
 class SkBitmap;
 class SkCanvas;
 class SkImage;
 struct SkImageInfo;
 class SkPaint;
 class SkPixmap;
@@ skipping 118 matching lines @@
 
 private:
     const SkSurfaceProps fProps;
     const SkIRect        fSubset;
     const uint32_t       fUniqueID;
 
     typedef SkRefCnt INHERITED;
 };
 
 #endif