fix(facade): workaround for lack of Symbol.iterator in es6-shim

Closes angular#4219
Fixes angular#4216

Author: marclaval

modules/angular2/src/core/compiler/query_list.ts

@@ -1,4 +1,6 @@
 import {ListWrapper, MapWrapper} from 'angular2/src/core/facade/collection';
+import {getSymbolIterator} from 'angular2/src/core/facade/lang';
+
 
 /**
  * An iterable and observable live list of components in the DOM.
@@ -101,7 +103,7 @@ export class QueryList<T> {
 
   map<U>(fn: (item: T) => U): U[] { return this._results.map(fn); }
 
-  [Symbol.iterator](): any { return this._results[Symbol.iterator](); }
+  [getSymbolIterator()](): any { return this._results[getSymbolIterator()](); }
 
   // Internal to the framework.
   fireCallbacks(): void {

modules/angular2/src/core/facade/collection.ts

@@ -1,4 +1,11 @@
-import {isJsObject, global, isPresent, isBlank, isArray} from 'angular2/src/core/facade/lang';
+import {
+  isJsObject,
+  global,
+  isPresent,
+  isBlank,
+  isArray,
+  getSymbolIterator
+} from 'angular2/src/core/facade/lang';
 
 export var Map = global.Map;
 export var Set = global.Set;
@@ -289,8 +296,8 @@ export class ListWrapper {
 export function isListLikeIterable(obj: any): boolean {
   if (!isJsObject(obj)) return false;
   return isArray(obj) ||
-         (!(obj instanceof Map) &&  // JS Map are iterables but return entries as [k, v]
-          Symbol.iterator in obj);  // JS Iterable have a Symbol.iterator prop
+         (!(obj instanceof Map) &&      // JS Map are iterables but return entries as [k, v]
+          getSymbolIterator() in obj);  // JS Iterable have a Symbol.iterator prop
 }
 
 export function iterateListLike(obj: any, fn: Function) {
@@ -299,7 +306,7 @@ export function iterateListLike(obj: any, fn: Function) {
       fn(obj[i]);
     }
   } else {
-    var iterator = obj[Symbol.iterator]();
+    var iterator = obj[getSymbolIterator()]();
     var item;
     while (!((item = iterator.next()).done)) {
       fn(item.value);

modules/angular2/src/core/facade/lang.ts

@@ -351,3 +351,24 @@ export function setValueOnPath(global: any, path: string, value: any) {
   }
   obj[parts.shift()] = value;
 }
+
+// When Symbol.iterator doesn't exist, retrieves the key used in es6-shim
+var _symbolIterator = null;
+export function getSymbolIterator(): string | symbol {
+  if (isBlank(_symbolIterator)) {
+    if (isPresent(Symbol) && isPresent(Symbol.iterator)) {
+      _symbolIterator = Symbol.iterator;
+    } else {
+      // es6-shim specific logic
+      var keys = Object.getOwnPropertyNames(Map.prototype);
+      for (var i = 0; i < keys.length; ++i) {
+        var key = keys[i];
+        if (key !== 'entries' && key !== 'size' &&
+            Map.prototype[key] === Map.prototype['entries']) {
+          _symbolIterator = key;
+        }
+      }
+    }
+  }
+  return _symbolIterator;
+}

modules/angular2/test/core/change_detection/iterable.ts

@@ -1,7 +1,8 @@
+import {getSymbolIterator} from 'angular2/src/core/facade/lang';
 
 export class TestIterable {
   list: number[];
   constructor() { this.list = []; }
 
-  [Symbol.iterator]() { return this.list[Symbol.iterator](); }
+  [getSymbolIterator()]() { return this.list[getSymbolIterator()](); }
 }