Treat Object and dynamic similarly

lib/runtime/dart/collection.js

 var collection;
 (function(exports) {
   'use strict';
   let _source = Symbol('_source');
   let UnmodifiableListView$ = dart.generic(function(E) {
     class UnmodifiableListView extends _internal.UnmodifiableListBase$(E) {
       UnmodifiableListView(source) {
         this[_source] = source;
         super.UnmodifiableListBase();
       }
@@ skipping 101 matching lines @@
           toRemove.remove(o);
         }
         this.removeAll(toRemove);
       }
       removeWhere(test) {
         let toRemove = new List.from([]);
         for (let element of this) {
           if (test(element))
             toRemove.add(element);
         }
-        this.removeAll(dart.as(toRemove, core.Iterable$(core.Object)));
+        this.removeAll(toRemove);
       }
       retainWhere(test) {
         let toRemove = new List.from([]);
         for (let element of this) {
           if (!dart.notNull(test(element)))
             toRemove.add(element);
         }
-        this.removeAll(dart.as(toRemove, core.Iterable$(core.Object)));
+        this.removeAll(toRemove);
       }
       containsAll(other) {
         for (let o of other) {
           if (!dart.notNull(this.contains(o)))
             return false;
         }
         return true;
       }
       union(other) {
         return ((_) => {
@@ skipping 4747 matching lines @@
   exports.LinkedHashMapKeyIterable = LinkedHashMapKeyIterable;
   exports.LinkedHashMapKeyIterable$ = LinkedHashMapKeyIterable$;
   exports.LinkedHashMapKeyIterator = LinkedHashMapKeyIterator;
   exports.LinkedHashMapKeyIterator$ = LinkedHashMapKeyIterator$;
   exports.HashSetIterator = HashSetIterator;
   exports.HashSetIterator$ = HashSetIterator$;
   exports.LinkedHashSetCell = LinkedHashSetCell;
   exports.LinkedHashSetIterator = LinkedHashSetIterator;
   exports.LinkedHashSetIterator$ = LinkedHashSetIterator$;
 })(collection || (collection = {}));