[Bug] Disabled entry field shows dotted border on iOS with Visual="Material" applied

Description

Different visual effect in the Entry element when it is using Material design and being disabled.

Steps to Reproduce

1. Create an Entry on the page
2. Set the Visual="Material"
3. Set the IsEnabled = "False"

Expected Behavior

The entry should have dotted border both iOS and Android.

Actual Behavior

The dotted border is working on iOS when disabled but not Android; on Android it is rendering just as normal border as it does like the filed is enabled.

Basic Information

• Version with issue: Xamarin.Forms.Visual.Material v3.6.0.220655 and v3.6.0.293080
• IDE: Visual Studio 2017 v15.9.9
• Platform Target Frameworks:
  • iOS: 12.2
  • Android: 9.0 api 28
  • UWP:
• Android Support Library Version:
• Nuget Packages: Xamarin.Forms.Visual.Material v3.6.0.220655 and v3.6.0.293080
• Affected Devices: emulators -> iPhone Xr , Pixel xl

Screenshots

Reproduction Link

https://github.com/davidortinau/TheLittleThingsPlayground/ I was using this repo TheLittleThingsPlayground to replicate the problem. Thanks to David.

Just navigate to the visual of Entry (https://github.com/davidortinau/TheLittleThingsPlayground/blob/master/TheLittleThingsPlayground/Views/Visual/EntriesPage.xaml) and set IsEnabled to False.

            <Entry Placeholder="Title" Text="Vintage Dress" IsEnabled="False"
                   PlaceholderColor="{StaticResource QuinaryColor}" TextColor="{StaticResource PrimaryColor}" BackgroundColor="#ddd"
                   FlexLayout.Basis="100%" Margin="0,0,0,10" />