Make ValueFrame.Priority non-virtual.

src/Avalonia.Base/PropertyStore/ImmediateValueFrame.cs

@@ -15,7 +15,6 @@ namespace Avalonia.PropertyStore
         }
 
         public override bool IsActive => true;
-        public override BindingPriority Priority { get; }
 
         public BindingEntry<T> AddBinding<T>(
             StyledPropertyBase<T> property,

src/Avalonia.Base/PropertyStore/ValueFrame.cs

@@ -12,7 +12,7 @@ namespace Avalonia.PropertyStore
         public int EntryCount => _entries.Count;
         public abstract bool IsActive { get; }
         public ValueStore? Owner { get; private set; }
-        public abstract BindingPriority Priority { get; }
+        public BindingPriority Priority { get; protected set; }
 
         public bool Contains(AvaloniaProperty property) => _entries.Contains(property);
 

src/Avalonia.Base/Styling/StyleInstance.cs

@@ -40,7 +40,6 @@ namespace Avalonia.Styling
             }
         }
 
-        public override BindingPriority Priority { get; }
         public IStyle Source { get; }
 
         public void Add(ISetterInstance instance)