[UWP] Don't block the UI thread when invalidating (#1468)

scripts/azure-pipelines.yml

@@ -695,7 +695,7 @@ stages:
           parameters:
             name: native_checks_windows
             displayName: Run Code Checks
-            # condition: and(always(), eq('refs/heads/master', variables['Build.SourceBranch']))
+            condition: and(always(), eq('refs/heads/master', variables['Build.SourceBranch']))
             vmImage: $(VM_IMAGE_WINDOWS_PREVIOUS)
             target: git-sync-deps
             installWindowsSdk: false

source/SkiaSharp.Views/SkiaSharp.Views.UWP/SKXamlCanvas.cs

@@ -116,10 +116,7 @@ namespace SkiaSharp.Views.UWP
 
 		public void Invalidate()
 		{
-			if (Dispatcher.HasThreadAccess)
-				DoInvalidate();
-			else
-				Dispatcher.RunAsync(CoreDispatcherPriority.Normal, DoInvalidate).AsTask().Wait();
+			Dispatcher.RunAsync(CoreDispatcherPriority.Normal, DoInvalidate);
 		}
 
 		private void DoInvalidate()