cleanup(change_detection): make Locals private

Closes #4321

modules/angular2/src/core/change_detection/parser/locals.ts

@@ -2,6 +2,9 @@ import {isPresent} from 'angular2/src/core/facade/lang';
 import {BaseException} from 'angular2/src/core/facade/exceptions';
 import {ListWrapper, MapWrapper} from 'angular2/src/core/facade/collection';
 
+/**
+ * @private
+ */
 export class Locals {
   constructor(public parent: Locals, public current: Map<any, any>) {}