Revert "Add "last" setter to List."

third_party/pkg/js/lib/src/wrapping/js/array_to_list_adapter.dart

Index: third_party/pkg/js/lib/src/wrapping/js/array_to_list_adapter.dart
diff --git a/third_party/pkg/js/lib/src/wrapping/js/array_to_list_adapter.dart b/third_party/pkg/js/lib/src/wrapping/js/array_to_list_adapter.dart
index a2aefa902a1d619b823f7dd7302b34c1b1b14f66..95660bbae9e4989b5a88d0c39cc7f0cef11c8c82 100644
--- a/third_party/pkg/js/lib/src/wrapping/js/array_to_list_adapter.dart
+++ b/third_party/pkg/js/lib/src/wrapping/js/array_to_list_adapter.dart
@@ -34,15 +34,12 @@ class JsArrayToListAdapter<E> extends TypedProxy /*with ListMixin<E>*/
   @override Iterator<E> get iterator => new _JsIterator<E>(this);
   @override int get length => $unsafe.length;
 
-  // List
-  @override void set last(E value) {
-    if (length == 0) throw new StateError("No element");
-    this[length - 1] = value;
-  }
+  // Collection
   @override void add(E value) { $unsafe.push(_toJs(value)); }
   @override void clear() { this.length = 0; }
   @override bool remove(Object element) => removeAt(indexOf(element)) != null;
 
+  // List
   @override E operator [](int index) {
     if (index < 0 || index >= this.length) throw new RangeError.value(index);
     return _fromJs($unsafe[index]);