fix icon_theme.cs

com.unity.uiwidgets/Runtime/widgets/icon_theme.cs

 using Unity.UIWidgets.foundation;
 
 namespace Unity.UIWidgets.widgets {
-    public class IconTheme : InheritedWidget {
+    public class IconTheme : InheritedTheme {
         public IconTheme(
             Key key = null,
             IconThemeData data = null,
 
         public static IconThemeData of(BuildContext context) {
             IconThemeData iconThemeData = _getInheritedIconThemeData(context);
-            return iconThemeData.isConcrete ? iconThemeData : IconThemeData.fallback().merge(iconThemeData);
+            return iconThemeData.isConcrete ? iconThemeData : 
+                iconThemeData.copyWith(
+                    size: iconThemeData.size ??  IconThemeData.fallback().size,
+                    color: iconThemeData.color ??  IconThemeData.fallback().color,
+                    opacity: iconThemeData.opacity ??  IconThemeData.fallback().opacity
+                );
-            IconTheme iconTheme = (IconTheme) context.inheritFromWidgetOfExactType(typeof(IconTheme));
+            IconTheme iconTheme = (IconTheme) context.dependOnInheritedWidgetOfExactType<IconTheme>();
             if (iconTheme != null) {
                 return iconTheme.data;
             }
 
         public override void debugFillProperties(DiagnosticPropertiesBuilder properties) {
             base.debugFillProperties(properties);
-            properties.add(new DiagnosticsProperty<IconThemeData>("data", data, showName: false));
+            data.debugFillProperties(properties);
+        }
+
+        public override Widget wrap(BuildContext context, Widget child) {
+            IconTheme iconTheme = context.findAncestorWidgetOfExactType<IconTheme>();
+            return this == iconTheme ? child : new IconTheme(data: data, child: child);
         }
     }
 }