Extract the SVG Filter Reference implementation out of the FilterEffectRenderer into its own type

Source/core/core.gypi

 {
     'variables': {
         'core_idl_files': [
             'css/CSS.idl',
             'css/CSSCharsetRule.idl',
             'css/CSSFontFaceLoadEvent.idl',
             'css/CSSFontFaceRule.idl',
             'css/CSSHostRule.idl',
             'css/CSSImportRule.idl',
             'css/CSSMediaRule.idl',
@@ skipping 2891 matching lines @@
             'platform/graphics/filters/Filter.h',
             'platform/graphics/filters/FilterEffect.cpp',
             'platform/graphics/filters/FilterEffect.h',
             'platform/graphics/filters/FilterOperation.cpp',
             'platform/graphics/filters/FilterOperation.h',
             'platform/graphics/filters/FilterOperations.cpp',
             'platform/graphics/filters/FilterOperations.h',
             'platform/graphics/filters/LightSource.h',
             'platform/graphics/filters/PointLightSource.cpp',
             'platform/graphics/filters/PointLightSource.h',
+            'platform/graphics/filters/ReferenceFilter.cpp',
+            'platform/graphics/filters/ReferenceFilter.h',
             'platform/graphics/filters/SkiaImageFilterBuilder.cpp',
             'platform/graphics/filters/SkiaImageFilterBuilder.h',
             'platform/graphics/filters/SourceAlpha.cpp',
             'platform/graphics/filters/SourceAlpha.h',
             'platform/graphics/filters/SourceGraphic.cpp',
             'platform/graphics/filters/SourceGraphic.h',
             'platform/graphics/filters/SpotLightSource.cpp',
             'platform/graphics/filters/SpotLightSource.h',
             'platform/graphics/gpu/DrawingBuffer.cpp',
             'platform/graphics/gpu/DrawingBuffer.h',
@@ skipping 238 matching lines @@
             'platform/graphics/IntRect.cpp',
             'platform/graphics/IntRectExtent.h',
             'platform/graphics/LayoutRect.cpp',
             'platform/graphics/Region.cpp',
             'platform/graphics/transforms/TransformationMatrix.cpp',
             'platform/graphics/transforms/AffineTransform.cpp',
         ],
         'webcore_svg_files': [
             'rendering/style/SVGRenderStyle.cpp',
             'rendering/style/SVGRenderStyleDefs.cpp',
+            'rendering/svg/ReferenceFilterBuilder.cpp',
+            'rendering/svg/ReferenceFilterBuilder.h',
             'rendering/svg/RenderSVGBlock.cpp',
             'rendering/svg/RenderSVGBlock.h',
             'rendering/svg/RenderSVGContainer.cpp',
             'rendering/svg/RenderSVGContainer.h',
             'rendering/svg/RenderSVGEllipse.cpp',
             'rendering/svg/RenderSVGEllipse.h',
             'rendering/svg/RenderSVGForeignObject.cpp',
             'rendering/svg/RenderSVGForeignObject.h',
             'rendering/svg/RenderSVGGradientStop.cpp',
             'rendering/svg/RenderSVGGradientStop.h',
@@ skipping 533 matching lines @@
                 'bison_exe': 'bison',
                 # We specify a preprocess so it happens locally and won't get
                 # distributed to goma.
                 # FIXME: /usr/bin/gcc won't exist on OSX forever. We want to
                 # use /usr/bin/clang once we require Xcode 4.x.
                 'preprocessor': '--preprocessor "/usr/bin/gcc -E -P -x c++"'
               }],
          ],
     }
 }