Removed LINQ from MeasureOverride.

And removed empty MeasureOverride methods.

src/Perspex.Controls/Primitives/ScrollBar.cs

@@ -72,12 +72,6 @@ namespace Perspex.Controls.Primitives
             set { SetValue(OrientationProperty, value); }
         }
 
-        /// <inheritdoc/>
-        protected override Size MeasureOverride(Size availableSize)
-        {
-            return base.MeasureOverride(availableSize);
-        }
-
         /// <summary>
         /// Calculates whether the scrollbar should be visible.
         /// </summary>

src/Perspex.Controls/ScrollViewer.cs

@@ -231,12 +231,6 @@ namespace Perspex.Controls
             return new Vector(Clamp(offset.X, 0, maxX), Clamp(offset.Y, 0, maxY));
         }
 
-        /// <inheritdoc/>
-        protected override Size MeasureOverride(Size availableSize)
-        {
-            return base.MeasureOverride(availableSize);
-        }
-
         private static double Clamp(double value, double min, double max)
         {
             return (value < min) ? min : (value > max) ? max : value;

src/Perspex.Layout/Layoutable.cs

@@ -490,7 +490,7 @@ namespace Perspex.Layout
             double width = 0;
             double height = 0;
 
-            foreach (ILayoutable child in this.GetVisualChildren().OfType<ILayoutable>())
+            foreach (ILayoutable child in this.GetVisualChildren())
             {
                 child.Measure(availableSize);
                 width = Math.Max(width, child.DesiredSize.Width);