Fix build

Xamarin.Forms.Platform.Android/AppCompat/MasterDetailContainer.cs

@@ -32,13 +32,14 @@ namespace Xamarin.Forms.Platform.Android.AppCompat
 			{
 				if (_isMaster)
 				{
-					var width = (int)Context.ToPixels(_parent.MasterBounds.Width);
-                    // When the base class computes the size of the Master container, it starts at the top of the 
-                    // screen and adds padding (_parent.MasterBounds.Top) to leave room for the status bar
-                    // When this container is laid out, it's already starting from the adjusted y value of the parent,
-                    // so we subtract _parent.MasterBounds.Top from our starting point (to get 0) and add it to the 
-                    // bottom (so the master page stretches to the bottom of the screen)
-					var height = (int)Context.ToPixels(_parent.MasterBounds.Height + _parent.MasterBounds.Top); 
+					var controller = (IMasterDetailPageController)_parent;
+					var width = (int)Context.ToPixels(controller.MasterBounds.Width);
+					// When the base class computes the size of the Master container, it starts at the top of the 
+					// screen and adds padding (_parent.MasterBounds.Top) to leave room for the status bar
+					// When this container is laid out, it's already starting from the adjusted y value of the parent,
+					// so we subtract _parent.MasterBounds.Top from our starting point (to get 0) and add it to the 
+					// bottom (so the master page stretches to the bottom of the screen)
+					var height = (int)Context.ToPixels(controller.MasterBounds.Height + controller.MasterBounds.Top);
 					_pageContainer.Layout(0, 0, width, height);
 				}
 				else