Move check to avalonia properties.

src/Avalonia.Base/AvaloniaPropertyRegistry.cs

@@ -448,11 +448,6 @@ namespace Avalonia
 
             foreach (PropertyInitializationData data in initializationData)
             {
-                if (!data.Property.HasNotifyInitializedObservers)
-                {
-                    continue;
-                }
-
                 data.Property.NotifyInitialized(o);
             }
         }

src/Avalonia.Base/DirectPropertyBase.cs

@@ -104,13 +104,16 @@ namespace Avalonia
         /// <inheritdoc/>
         internal override void NotifyInitialized(IAvaloniaObject o)
         {
-            var e = new AvaloniaPropertyChangedEventArgs<TValue>(
+            if (HasNotifyInitializedObservers)
-                o,
+            {
-                this,
+                var e = new AvaloniaPropertyChangedEventArgs<TValue>(
-                default,
+                    o,
-                InvokeGetter(o),
+                    this,
-                BindingPriority.Unset);
+                    default,
-            NotifyInitialized(e);
+                    InvokeGetter(o),
+                    BindingPriority.Unset);
+                NotifyInitialized(e);
+            }
         }
 
         /// <inheritdoc/>

src/Avalonia.Base/StyledPropertyBase.cs

@@ -141,13 +141,16 @@ namespace Avalonia
         /// <inheritdoc/>
         internal override void NotifyInitialized(IAvaloniaObject o)
         {
-            var e = new AvaloniaPropertyChangedEventArgs<TValue>(
+            if (HasNotifyInitializedObservers)
-                o,
+            {
-                this,
+                var e = new AvaloniaPropertyChangedEventArgs<TValue>(
-                default,
+                    o,
-                o.GetValue(this),
+                    this,
-                BindingPriority.Unset);
+                    default,
-            NotifyInitialized(e);
+                    o.GetValue(this),
+                    BindingPriority.Unset);
+                NotifyInitialized(e);
+            }
         }
 
         /// <inheritdoc/>