fix some marked errors

com.unity.uiwidgets/Runtime/rendering/paragraph.cs

                 textWidthBasis: textWidthBasis,
                 textHeightBehavior: textHeightBehavior
             );
-            //addAll(children);[!!!]?
+            addAll(children);
             _extractPlaceholderSpans(text);
         }
 
                 paintParagraph(context, offset);
             }
         } */
-        // need to replace it?
+        // [!!!]need to replace it?
         
         public override void paint(PaintingContext context, Offset offset) {
               _layoutTextWithConstraints(constraints);

com.unity.uiwidgets/Runtime/rendering/proxy_box.cs

             _borderRadius = borderRadius;
         }
         
-        public PhysicalModelLayer layer { // [!!!] override
+        public new PhysicalModelLayer layer {
             get {
                 return base.layer as PhysicalModelLayer;
             }
             D.assert(elevation >= 0.0);
         }
 
-        public PhysicalModelLayer layer { // [!!!] override
+        public new PhysicalModelLayer layer {
             get {
                 return base.layer as PhysicalModelLayer;
             }
             get { return true; }
         }
 
-        public FollowerLayer layer { // [!!!] override
+        public new FollowerLayer layer {
             get {
                 return base.layer as FollowerLayer;
             }