Fix crash iOS Label measure for RTL languages (#15605)

* Update UIViewExtensions.cs

* Add token for provisionator

# Conflicts:
#	build/steps/build-windows.yml

* Update Platform.cs (#15601)

Co-authored-by: Rui Marinho <me@ruimarinho.net>

Xamarin.Forms.Platform.iOS/Extensions/UIViewExtensions.cs

@@ -88,8 +88,18 @@ internal static IEnumerable<UIView> DescendantsTree(this UIView self)
 			else
 				s = self.FittingSize;
 #endif
-			var request = new Size(s.Width == float.PositiveInfinity ? double.PositiveInfinity : s.Width,
-				s.Height == float.PositiveInfinity ? double.PositiveInfinity : s.Height);
+
+			var width = s.Width;
+			var height = s.Height;
+
+			if (nfloat.IsNaN(width))
+				width = float.PositiveInfinity;
+
+			if (nfloat.IsNaN(height))
+				height = float.PositiveInfinity;
+
+			var request = new Size(width == float.PositiveInfinity ? double.PositiveInfinity : width,
+				height == float.PositiveInfinity ? double.PositiveInfinity : height);
 			var minimum = new Size(minimumWidth < 0 ? request.Width : minimumWidth,
 				minimumHeight < 0 ? request.Height : minimumHeight);
 			return new SizeRequest(request, minimum);