Added ResourcesChangedEventArgs.Empty.

We don't need to allocate a new instance each time.

src/Avalonia.Controls/Application.cs

@@ -260,7 +260,7 @@ namespace Avalonia
             try
             {
                 _notifyingResourcesChanged = true;
-                ResourcesChanged?.Invoke(this, new ResourcesChangedEventArgs());
+                ResourcesChanged?.Invoke(this, ResourcesChangedEventArgs.Empty);
             }
             finally
             {

src/Avalonia.Styling/Controls/ResourceDictionary.cs

@@ -146,7 +146,7 @@ namespace Avalonia.Controls
 
             if (hasResources)
             {
-                owner.NotifyHostedResourcesChanged(new ResourcesChangedEventArgs());
+                owner.NotifyHostedResourcesChanged(ResourcesChangedEventArgs.Empty);
             }
         }
 
@@ -171,14 +171,14 @@ namespace Avalonia.Controls
 
                 if (hasResources)
                 {
-                    owner.NotifyHostedResourcesChanged(new ResourcesChangedEventArgs());
+                    owner.NotifyHostedResourcesChanged(ResourcesChangedEventArgs.Empty);
                 }
             }
         }
 
         private void OnCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
         {
-            Owner?.NotifyHostedResourcesChanged(new ResourcesChangedEventArgs());
+            Owner?.NotifyHostedResourcesChanged(ResourcesChangedEventArgs.Empty);
         }
     }
 }

src/Avalonia.Styling/Controls/ResourcesChangedEventArgs.cs

@@ -4,5 +4,6 @@ namespace Avalonia.Controls
 {
     public class ResourcesChangedEventArgs : EventArgs
     {
+        public static new readonly ResourcesChangedEventArgs Empty = new ResourcesChangedEventArgs();
     }
 }

src/Avalonia.Styling/StyledElement.cs

@@ -509,7 +509,7 @@ namespace Avalonia
 
                 if (count > 0)
                 {
-                    e ??= new ResourcesChangedEventArgs();
+                    e ??= ResourcesChangedEventArgs.Empty;
 
                     for (var i = 0; i < count; ++i)
                     {
@@ -803,13 +803,13 @@ namespace Avalonia
         {
             if (ResourcesChanged is object)
             {
-                e ??= new ResourcesChangedEventArgs();
+                e ??= ResourcesChangedEventArgs.Empty;
                 ResourcesChanged(this, e);
             }
 
             if (propagate)
             {
-                e ??= new ResourcesChangedEventArgs();
+                e ??= ResourcesChangedEventArgs.Empty;
                 NotifyChildResourcesChanged(e);
             }
         }

src/Avalonia.Styling/Styling/Style.cs

@@ -67,7 +67,7 @@ namespace Avalonia.Styling
 
                     if (hadResources || _resources.HasResources)
                     {
-                        Owner.NotifyHostedResourcesChanged(new ResourcesChangedEventArgs());
+                        Owner.NotifyHostedResourcesChanged(ResourcesChangedEventArgs.Empty);
                     }
                 }
             }