Fix non-compiling tests.

src/Avalonia.Visuals/Rendering/DirtyRects.cs

@@ -17,9 +17,9 @@ namespace Avalonia.Rendering
             {
                 for (var i = 0; i < _rects.Count; ++i)
                 {
-                    var r = _rects[i].Inflate(1);
+                    var r = _rects[i];
 
-                    if (r.Intersects(rect))
+                    if (r.Inflate(1).Intersects(rect))
                     {
                         _rects[i] = r.Union(rect);
                         return;

tests/Avalonia.Visuals.UnitTests/Rendering/SceneGraph/SceneBuilderTests.cs

@@ -443,7 +443,7 @@ namespace Avalonia.Visuals.UnitTests.Rendering.SceneGraph
                 var dirty = new DirtyRects();
                 SceneBuilder.Update(scene, decorator, dirty);
 
-                var rects = dirty.Coalesce().ToArray();
+                var rects = dirty.ToArray();
                 Assert.Equal(new[] { new Rect(0, 10, 100, 90) }, rects);
             }
         }