Cache property metadata in effective value.

Decreases the number of metadata lookups needed. Previously we were doing two lookups on construction now we're only doing one.

src/Avalonia.Base/PropertyStore/EffectiveValue`1.cs

@@ -15,22 +15,19 @@ namespace Avalonia.PropertyStore
     /// </remarks>
     internal sealed class EffectiveValue<T> : EffectiveValue
     {
+        private readonly StyledPropertyMetadata<T> _metadata;
         private T? _baseValue;
         private UncommonFields? _uncommon;
 
-        public EffectiveValue(
-            AvaloniaObject owner,
-            StyledPropertyBase<T> property,
-            T value, 
-            BindingPriority priority)
+        public EffectiveValue(AvaloniaObject owner, StyledPropertyBase<T> property)
         {
-            Value = value;
-            Priority = priority;
+            Priority = BindingPriority.Unset;
             BasePriority = BindingPriority.Unset;
+            _metadata = property.GetMetadata(owner.GetType());
 
-            if (property.HasCoercion &&
-                property.GetMetadata(owner.GetType()) is { } metadata &&
-                metadata.CoerceValue is { } coerce)
+            var value = _metadata.DefaultValue;
+
+            if (property.HasCoercion && _metadata.CoerceValue is { } coerce)
             {
                 _uncommon = new()
                 {
@@ -39,7 +36,11 @@ namespace Avalonia.PropertyStore
                     _uncoercedBaseValue = value,
                 };
 
-                value = coerce(owner, value);
+                Value = coerce(owner, value);
+            }
+            else
+            {
+                Value = value;
             }
         }
 
@@ -82,8 +83,8 @@ namespace Avalonia.PropertyStore
             Debug.Assert(oldValue is not null || newValue is not null);
 
             var p = (StyledPropertyBase<T>)property;
-            var o = oldValue is not null ? ((EffectiveValue<T>)oldValue).Value : p.GetDefaultValue(owner.GetType());
-            var n = newValue is not null ? ((EffectiveValue<T>)newValue).Value : p.GetDefaultValue(owner.GetType());
+            var o = oldValue is not null ? ((EffectiveValue<T>)oldValue).Value : _metadata.DefaultValue;
+            var n = newValue is not null ? ((EffectiveValue<T>)newValue).Value : _metadata.DefaultValue;
             var priority = newValue is not null ? BindingPriority.Inherited : BindingPriority.Unset;
 
             if (!EqualityComparer<T>.Default.Equals(o, n))
@@ -131,7 +132,7 @@ namespace Avalonia.PropertyStore
             }
             else
             {
-                oldValue = property.GetDefaultValue(owner.GetType());
+                oldValue = _metadata.DefaultValue;
                 priority = BindingPriority.Unset;
             }
 

src/Avalonia.Base/PropertyStore/ValueStore.cs

@@ -182,8 +182,7 @@ namespace Avalonia.PropertyStore
                 }
                 else
                 {
-                    var defaultValue = property.GetDefaultValue(Owner.GetType());
-                    var effectiveValue = new EffectiveValue<T>(Owner, property, defaultValue, BindingPriority.Unset);
+                    var effectiveValue = new EffectiveValue<T>(Owner, property);
                     AddEffectiveValue(property, effectiveValue);
                     effectiveValue.SetAndRaise(this, result, priority);
                 }
@@ -199,8 +198,7 @@ namespace Avalonia.PropertyStore
                 }
                 else
                 {
-                    var defaultValue = property.GetDefaultValue(Owner.GetType());
-                    var effectiveValue = new EffectiveValue<T>(Owner, property, defaultValue, BindingPriority.Unset);
+                    var effectiveValue = new EffectiveValue<T>(Owner, property);
                     AddEffectiveValue(property, effectiveValue);
                     effectiveValue.SetLocalValueAndRaise(this, property, value);
                 }

src/Avalonia.Base/StyledPropertyBase.cs

@@ -183,7 +183,7 @@ namespace Avalonia
 
         internal override EffectiveValue CreateEffectiveValue(AvaloniaObject o)
         {
-            return new EffectiveValue<TValue>(o, this, GetDefaultValue(o.GetType()), BindingPriority.Unset);
+            return new EffectiveValue<TValue>(o, this);
         }
 
         /// <inheritdoc/>