Merge ReferenceFilter into Filter

Source/platform/blink_platform.gypi

 {
   'includes': [
     'platform_generated.gypi',
   ],
   'variables': {
     'platform_files': [
       'AsyncFileSystemCallbacks.h',
       'CalculationValue.h',
       'CheckedInt.h',
       'Clock.cpp',
@@ skipping 597 matching lines @@
       'graphics/filters/FEMorphology.cpp',
       'graphics/filters/FEMorphology.h',
       'graphics/filters/FEOffset.cpp',
       'graphics/filters/FEOffset.h',
       'graphics/filters/FESpecularLighting.cpp',
       'graphics/filters/FESpecularLighting.h',
       'graphics/filters/FETile.cpp',
       'graphics/filters/FETile.h',
       'graphics/filters/FETurbulence.cpp',
       'graphics/filters/FETurbulence.h',
+      'graphics/filters/Filter.cpp',
       'graphics/filters/Filter.h',
       'graphics/filters/FilterEffect.cpp',
       'graphics/filters/FilterEffect.h',
       'graphics/filters/FilterOperation.cpp',
       'graphics/filters/FilterOperation.h',
       'graphics/filters/FilterOperations.cpp',
       'graphics/filters/FilterOperations.h',
       'graphics/filters/LightSource.cpp',
       'graphics/filters/LightSource.h',
       'graphics/filters/PointLightSource.cpp',
       'graphics/filters/PointLightSource.h',
-      'graphics/filters/ReferenceFilter.cpp',
-      'graphics/filters/ReferenceFilter.h',
       'graphics/filters/SkiaImageFilterBuilder.cpp',
       'graphics/filters/SkiaImageFilterBuilder.h',
       'graphics/filters/SourceAlpha.cpp',
       'graphics/filters/SourceAlpha.h',
       'graphics/filters/SourceGraphic.cpp',
       'graphics/filters/SourceGraphic.h',
       'graphics/filters/SpotLightSource.cpp',
       'graphics/filters/SpotLightSource.h',
       'graphics/gpu/AcceleratedImageBufferSurface.cpp',
       'graphics/gpu/AcceleratedImageBufferSurface.h',
@@ skipping 418 matching lines @@
       ['os_posix==1 and OS!="mac"',
         {
           'platform_test_files': [
             'text/LocaleICUTest.cpp',
           ],
         }
       ],
     ],
   },
 }