Update FloodFillHelper.cs

src/PixiEditor.ChangeableDocument/Changes/Drawing/FloodFill/FloodFillHelper.cs

@@ -6,6 +6,7 @@ using Drawie.Backend.Core.ColorsImpl;
 using Drawie.Backend.Core.Numerics;
 using Drawie.Backend.Core.Surfaces;
 using Drawie.Backend.Core.Surfaces.ImageData;
+using Drawie.Backend.Core.Surfaces.PaintImpl;
 using Drawie.Backend.Core.Vector;
 using Drawie.Numerics;