Merge pull request #6537 from unoplatform/dev/xygu/20210722/uwp-eleva…

…ted-view-no-shadow

fix(elevatedview): shadow not appearing on uwp

src/Uno.UI.Toolkit/ElevatedView.cs

@@ -198,7 +198,7 @@ private void UpdateElevation()
 				// it will get the right shape (with rounded corners)
 				_border.SetElevationInternal(Elevation, ShadowColor);
 #elif NETFX_CORE || NETCOREAPP
-				(ElevatedContent as DependencyObject).SetElevationInternal(Elevation, ShadowColor, _shadowHost as DependencyObject, CornerRadius);
+				_border.SetElevationInternal(Elevation, ShadowColor, _shadowHost as DependencyObject, CornerRadius);
 #endif
 			}
 		}