material fixes (8)

com.unity.uiwidgets/Runtime/gestures/multidrag.cs

 using System;
 using System.Collections.Generic;
+using System.Linq;
 using Unity.UIWidgets.async2;
 using Unity.UIWidgets.foundation;
 using Unity.UIWidgets.ui;
 
 
         public override void dispose() {
-            foreach (var key in _pointers.Keys) {
+            foreach (var key in _pointers.Keys.ToList()) {
                 _removeState(key);
             }
             D.assert(_pointers.isEmpty);

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

                     hasSameSuperclass = oldElementClass == newWidgetClass;
                     return true;
                 });
-                if (hasSameSuperclass && child.widget == newWidget) {
-                    if (child.slot != newSlot) {
+                if (hasSameSuperclass && Equals(child.widget,newWidget)) {
+                    if (!Equals(child.slot, newSlot)) {
                         updateSlotForChild(child, newSlot);
                     }
 
-                    if (child.slot != newSlot) {
+                    if (!Equals(child.slot, newSlot)) {
-                    D.assert(child.widget == newWidget);
+                    D.assert(Equals(child.widget, newWidget));
                     D.assert(() => {
                         child.owner._debugElementWasRebuilt(child);
                         return true;