feat(facade): add ListWrapper.toJSON method

Author: btford

modules/angular2/src/facade/collection.dart

@@ -1,9 +1,12 @@
 library facade.collection;
 
 import 'dart:collection' show IterableBase, Iterator;
+import 'dart:convert' show JsonEncoder;
 export 'dart:core' show Map, List, Set;
 import 'dart:math' show max, min;
 
+var jsonEncoder = new JsonEncoder();
+
 class MapIterator extends Iterator<List> {
  final Iterator _iterator;
  final Map _map;
@@ -170,6 +173,10 @@ class ListWrapper {
  }
  }
 
+ static String toJSON(List l) {
+ return jsonEncoder.convert(l);
+ }
+
  // JS splice, slice, fill functions can take start < 0 which indicates a position relative to
  // the end of the list
  static int _startOffset(List l, int start) {

modules/angular2/src/facade/collection.ts

@@ -238,6 +238,8 @@ export class ListWrapper {
  }
  }
  static toString<T>(l: List<T>): string { return l.toString(); }
+ static toJSON<T>(l: List<T>): string { return JSON.stringify(l); }
+
 }
 
 export function isListLikeIterable(obj): boolean {