Removing LineBreakMode support from WindowsResourcesProvider (#4024)

* Repro test page for 3979

* Removes LineBreakMode support from WindowsResourcesProvider as it is inconsistent with other platforms and caused issues when setting Span style to the default Device Styles

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue3979.xaml

@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<controls:TestContentPage
+			 xmlns:controls="clr-namespace:Xamarin.Forms.Controls"
+	         xmlns="http://xamarin.com/schemas/2014/forms"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             x:Class="Xamarin.Forms.Controls.Issues.Issue3979">
+	<ContentPage.Content>
+		<StackLayout>
+			<Label LineBreakMode="WordWrap">Clicking the button sets one of the spans in the following label to Device.Styles.BodyStyle. This test succeeds if clicking the button does not cause exception.</Label>
+			<Label>
+				<Label.FormattedText>
+					<FormattedString>
+						<Span Text="Red Bold, " TextColor="Red" FontAttributes="Bold" />
+						<Span Text="default, " x:Name="TargetSpan">
+							<Span.GestureRecognizers>
+								<TapGestureRecognizer Command="{Binding TapCommand}" />
+							</Span.GestureRecognizers>
+						</Span>
+						<Span Text="italic small." FontAttributes="Italic" FontSize="Small" />
+					</FormattedString>
+				</Label.FormattedText>
+			</Label>
+			<Button Clicked="Button_OnClicked" Text="Set style" />
+		</StackLayout>
+	</ContentPage.Content>
+</controls:TestContentPage>

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue3979.xaml.cs

@@ -0,0 +1,35 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+using Xamarin.Forms;
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+using Xamarin.Forms.Xaml;
+
+namespace Xamarin.Forms.Controls.Issues
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Github, 3979, "Issue Description", PlatformAffected.UWP)]
+	public partial class Issue3979 : TestContentPage // or TestMasterDetailPage, etc ...
+	{
+		public Issue3979()
+		{
+#if APP
+			InitializeComponent();
+#endif
+		}
+
+		protected override void Init()
+		{
+
+		}
+
+		private void Button_OnClicked(object sender, EventArgs e)
+		{
+			TargetSpan.Style = Device.Styles.BodyStyle;
+		}
+	}
+}

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems

@@ -395,6 +395,10 @@
     <Compile Include="$(MSBuildThisFileDirectory)Issue3541.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue3840.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue3913.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Issue3979.xaml.cs">
+      <DependentUpon>Issue3979.xaml</DependentUpon>
+      <SubType>Code</SubType>
+    </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)LegacyComponents\NonAppCompatSwitch.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)MapsModalCrash.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)ModalActivityIndicatorTest.cs" />
@@ -1007,4 +1011,10 @@
       <Generator>MSBuild:Compile</Generator>
     </EmbeddedResource>
   </ItemGroup>
+  <ItemGroup>
+    <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue3979.xaml">
+      <SubType>Designer</SubType>
+      <Generator>MSBuild:Compile</Generator>
+    </EmbeddedResource>
+  </ItemGroup>
 </Project>

Xamarin.Forms.Platform.UAP/WindowsResourcesProvider.cs

@@ -34,8 +34,7 @@ namespace Xamarin.Forms.Platform.UWP
 
 			formsStyle.Setters.Add(Label.FontSizeProperty, prototype.FontSize);
 			formsStyle.Setters.Add(Label.FontFamilyProperty, prototype.FontFamily.Source);
-			formsStyle.Setters.Add(Label.FontAttributesProperty, ToAttributes(prototype.FontWeight));
-			formsStyle.Setters.Add(Label.LineBreakModeProperty, ToLineBreakMode(prototype.TextWrapping));
+			formsStyle.Setters.Add(Label.FontAttributesProperty, ToAttributes(prototype.FontWeight));			
 
 			return formsStyle;
 		}
@@ -50,19 +49,5 @@ namespace Xamarin.Forms.Platform.UWP
 
 			return FontAttributes.None;
 		}
-
-		static LineBreakMode ToLineBreakMode(TextWrapping value)
-		{
-			switch (value)
-			{
-				case TextWrapping.Wrap:
-					return LineBreakMode.CharacterWrap;
-				case TextWrapping.WrapWholeWords:
-					return LineBreakMode.WordWrap;
-				default:
-				case TextWrapping.NoWrap:
-					return LineBreakMode.NoWrap;
-			}
-		}
 	}
 }