Fix and re-enable 2D failing feature tests.
https://dev.azure.com/dnceng/internal/_git/dotnet-wpf-test/pullrequest/1739?_a=overview disables failing feature tests.
The following test cases were disabled as they fail in .NET Core. they pass in .NET Framework: /Name="Color API Test" /SubArea="API Tests"
the following were disabled only for Windows Server 2008 R2 /Name="Line in Neg coordinates" /SubArea="Graphics Xaml Tests" /Name="Polygon in Neg coordinates" /SubArea="Graphics Xaml Tests" /Name="VisualXaml(BVThvLine.xaml,BVThvLine.png,True)" /SubArea="VisualXaml" /Name="VisualXaml(BVTPathStretch.xaml,BVTPathStretch.png,True)" /SubArea="VisualXaml" /Name="VisualXaml(BVTPolygonStretch.xaml,BVTPolygonStretch.png,True)" /SubArea="VisualXaml" /Name="VisualXaml(BVTPolylineStretch.xaml,BVTPolylineStretch.bmp,True)" /SubArea="VisualXaml" /Name="VisualXaml(P1ellipseImage.xaml,P1ellipseImage.bmp,True)" /SubArea="VisualXaml" /Name="VisualXaml(P1line.xaml,P1line.png,True)" /SubArea="VisualXaml"
cool Direct several issues