Merge pull request #1504 from smoogipoo/reduce-masking-calculations

Significantly reduce number of IsMaskedAway calculations

osu.Framework/Graphics/Drawable.cs

@@ -374,6 +374,9 @@ namespace osu.Framework.Graphics
         /// <returns>Whether masking calculations have taken place.</returns>
         public virtual bool UpdateSubTreeMasking(Drawable source, RectangleF maskingBounds)
         {
+            if (!IsPresent)
+                return false;
+
             if (HasProxy && source != proxy)
                 return false;