Fix mandatory break

src/Avalonia.Visuals/Media/TextFormatting/Unicode/LineBreakEnumerator.cs

@@ -96,7 +96,7 @@ namespace Avalonia.Media.TextFormatting.Unicode
                     if (_nextClass.Value == LineBreakClass.MandatoryBreak)
                     {
                         _lastPos = _pos;
-                        Current = new LineBreak(FindPriorNonWhitespace(_lastPos), _lastPos);
+                        Current = new LineBreak(FindPriorNonWhitespace(_lastPos), _lastPos, true);
                         return true;
                     }
 

tests/Avalonia.Skia.UnitTests/TextLayoutTests.cs

@@ -409,6 +409,8 @@ namespace Avalonia.Skia.UnitTests
         [InlineData("abcde\r\n", 7)] // Carriage Return + Line Feed
         [InlineData("abcde\n\r", 7)] // This isn't valid but we somehow have to support it.
         [InlineData("abcde\u000A", 6)] // Line Feed
+        [InlineData("abcde\u000B", 6)] // Vertical Tab
+        [InlineData("abcde\u000C", 6)] // Form Feed
         [InlineData("abcde\u000D", 6)] // Carriage Return
         public void Should_Break_With_BreakChar(string text, int expectedLength)
         {