Add methods for dispatching exceptions on osx.

src/Avalonia.Native/CallbackBase.cs

@@ -80,9 +80,11 @@ namespace Avalonia.Native
 
         public void RaiseException(Exception e)
         {
-            var exceptionInfo = ExceptionDispatchInfo.Capture(e);
+            var threadingInterface = AvaloniaLocator.Current.GetService<PlatformThreadingInterface>();
 
-            PlatformThreadingInterface.s_exceptionDispatchInfo = exceptionInfo;
+            threadingInterface.TerminateNativeApp();
+
+            threadingInterface.DispatchException(ExceptionDispatchInfo.Capture(e));
         }
     }
 }

src/Avalonia.Native/PlatformThreadingInterface.cs

@@ -13,8 +13,6 @@ namespace Avalonia.Native
 {
     public class PlatformThreadingInterface : IPlatformThreadingInterface
     {
-        public static ExceptionDispatchInfo s_exceptionDispatchInfo;
-
         class TimerCallback : CallbackBase, IAvnActionCallback
         {
             readonly Action _tick;
@@ -46,6 +44,7 @@ namespace Avalonia.Native
         }
 
         readonly IAvnPlatformThreadingInterface _native;
+        private ExceptionDispatchInfo _exceptionDispatchInfo;
 
         public PlatformThreadingInterface(IAvnPlatformThreadingInterface native)
         {
@@ -86,15 +85,23 @@ namespace Avalonia.Native
                     }
                 }
 
-                if(s_exceptionDispatchInfo != null)
+                if(_exceptionDispatchInfo != null)
                 {
-                    // TODO terminate NSApp.
+                    _exceptionDispatchInfo.Throw();
-
-                    s_exceptionDispatchInfo.Throw();
                 }
             }
         }
 
+        public void DispatchException (ExceptionDispatchInfo exceptionInfo)
+        {
+            _exceptionDispatchInfo = exceptionInfo;
+        }
+
+        public void TerminateNativeApp()
+        {
+            
+        }
+
         public void Signal(DispatcherPriority priority)
         {
             _native.Signal((int)priority);