Clean up render timers to use Environment.TickCount.

src/Avalonia.Visuals/Rendering/DefaultRenderTimer.cs

@@ -85,7 +85,7 @@ namespace Avalonia.Rendering
                 _runtime = AvaloniaLocator.Current.GetService<IRuntimePlatform>();
             }
 
-            return _runtime.StartSystemTimer(TimeSpan.FromSeconds(1.0 / FramesPerSecond), () => tick(Stopwatch.GetTimestamp()));
+            return _runtime.StartSystemTimer(TimeSpan.FromSeconds(1.0 / FramesPerSecond), () => tick(Environment.TickCount));
         }
 
         /// <summary>

src/Windows/Avalonia.Win32/RenderTimer.cs

@@ -34,7 +34,7 @@ namespace Avalonia.Win32
             EnsureTimerQueueCreated();
             var msPerFrame = 1000 / FramesPerSecond;
 
-            timerDelegate = (_, __) => tick(TimeStampToFrames());
+            timerDelegate = (_, __) => tick(Environment.TickCount);
 
             UnmanagedMethods.CreateTimerQueueTimer(
                 out var timer,