Remove DartConverter specializations for enums. Tonic provides a partial...

Remove DartConverter specializations for enums. Tonic provides a partial specialization for all enums. (#3160)

lib/ui/painting/canvas.h

@@ -18,15 +18,6 @@
 
 namespace tonic {
 class DartLibraryNatives;
-
-template <>
-struct DartConverter<SkCanvas::PointMode>
-    : public DartConverterInteger<SkCanvas::PointMode> {};
-
-template <>
-struct DartConverter<SkCanvas::VertexMode>
-    : public DartConverterInteger<SkCanvas::VertexMode> {};
-
 }  // namespace tonic
 
 namespace blink {

lib/ui/painting/gradient.h

@@ -13,11 +13,6 @@
 
 namespace tonic {
 class DartLibraryNatives;
-
-template <>
-struct DartConverter<SkShader::TileMode>
-    : public DartConverterInteger<SkShader::TileMode> {};
-
 }  // namspace tonic
 
 namespace blink {

lib/ui/painting/paint.h

@@ -31,10 +31,6 @@ class PaintData {};
 
 namespace tonic {
 
-template <>
-struct DartConverter<SkXfermode::Mode>
-    : public DartConverterInteger<SkXfermode::Mode> {};
-
 template <>
 struct DartConverter<blink::Paint> {
   static blink::Paint FromArguments(Dart_NativeArguments args,