V1.2.1 BUG: Opacity = 0 is still visible

In the latest release, if you set Opacity = 0 on a Label (I haven't tested anything else), the label is still visible on the View.

Repro

1. Create a new PCL project
2. Update Xamarin.Forms to v 1.2.1
3. Paste the below code into your App.cs

4. Run (only tested on Android)

   public class App
   {
       public static Page GetMainPage()
       {
           return new NavigationPage(new RootPage());
       }
   }
   
   public class RootPage : ContentPage
   {
       public RootPage()
       {
           var lbl1 = new Label
           {
               Text = "You should be able to see me!",
               VerticalOptions = LayoutOptions.CenterAndExpand,
               HorizontalOptions = LayoutOptions.CenterAndExpand,
           };
   
           var lbl2 = new Label
           {
               Text = "If you can see me, there's a bug!",
               Opacity = 0,
               VerticalOptions = LayoutOptions.CenterAndExpand,
               HorizontalOptions = LayoutOptions.CenterAndExpand,
           };
   
           Content = new StackLayout {Children = {lbl1, lbl2}};
       }
   }