fix build, correctly size UIScrollViews

Summary: Closes https://github.com/facebook/yoga/pull/626

Reviewed By: emilsjolander

Differential Revision: D5824425

Pulled By: splhack

fbshipit-source-id: e1a8dda5e86e2705afa7f6630a6757491a94c6d6

csharp/Facebook.Yoga/YogaNode.cs

@@ -595,12 +595,14 @@ namespace Facebook.Yoga
             Native.YGNodeSetBaselineFunc(_ygNode, _managedBaseline);
         }
 
-        public void CalculateLayout()
+        public void CalculateLayout(
+            float width = YogaConstants.Undefined, 
+            float height = YogaConstants.Undefined)
         {
             Native.YGNodeCalculateLayout(
                 _ygNode,
-                YogaConstants.Undefined,
-                YogaConstants.Undefined,
+                width,
+                height,
                 Native.YGNodeStyleGetDirection(_ygNode));
         }