feat(router): add CanDeactivate

modules/angular2/src/alt_router/interfaces.ts

@@ -3,4 +3,9 @@ import {RouteSegment, Tree} from './segments';
 export interface OnActivate {
   routerOnActivate(curr: RouteSegment, prev?: RouteSegment, currTree?: Tree<RouteSegment>,
                    prevTree?: Tree<RouteSegment>): void;
+}
+
+export interface CanDeactivate {
+  routerCanDeactivate(currTree?: Tree<RouteSegment>,
+                      futureTree?: Tree<RouteSegment>): Promise<boolean>;
 }

modules/angular2/src/alt_router/lifecycle_reflector.dart

@@ -1,5 +1,6 @@
 import './interfaces.dart';
 bool hasLifecycleHook(String name, Object obj) {
   if (name == "routerOnActivate") return obj is OnActivate;
+  if (name == "routerCanDeactivate") return obj is CanDeactivate;
   return false;
 }

modules/angular2/src/alt_router/lifecycle_reflector.ts

@@ -1,6 +1,7 @@
-import {Type} from 'angular2/src/facade/lang';
+import {Type, isBlank} from 'angular2/src/facade/lang';
 
 export function hasLifecycleHook(name: string, obj: Object): boolean {
+  if (isBlank(obj)) return false;
   let type = obj.constructor;
   if (!(type instanceof Type)) return false;
   return name in(<any>type).prototype;

modules/angular2/src/router/lifecycle/route_lifecycle_reflector.ts

@@ -1,4 +1,4 @@
-import {Type, isPresent} from 'angular2/src/facade/lang';
+import {Type, isBlank} from 'angular2/src/facade/lang';
 import {RouteLifecycleHook, CanActivate} from './lifecycle_annotations_impl';
 import {reflector} from 'angular2/src/core/reflection/reflection';