feat(change_detection): do not reparse AST when using generated detectors

modules/angular2/src/facade/collection.dart

@@ -134,6 +134,12 @@ class ListWrapper {
     list.forEach(fn);
   }
 
+  static void forEachWithIndex(List list, fn(item, index)) {
+    for (var i = 0; i < list.length; ++i) {
+      fn(list[i], i);
+    }
+  }
+
   static reduce(List list, fn(a, b), init) {
     return list.fold(init, fn);
   }

modules/angular2/src/facade/collection.ts

@@ -182,6 +182,11 @@ export class ListWrapper {
       fn(array[i]);
     }
   }
+  static forEachWithIndex<T>(array: List<T>, fn: (T, number) => void) {
+    for (var i = 0; i < array.length; i++) {
+      fn(array[i], i);
+    }
+  }
   static first<T>(array: List<T>): T {
     if (!array) return null;
     return array[0];