fix: Improve error message on missing dependency

modules/angular2/src/reflection/platform_reflection_capabilities.ts

@@ -0,0 +1,13 @@
+import {Type} from 'angular2/src/facade/lang';
+import {GetterFn, SetterFn, MethodFn} from './types';
+import {List} from 'angular2/src/facade/collection';
+
+export interface PlatformReflectionCapabilities {
+  factory(type: Type): Function;
+  interfaces(type: Type): List<any>;
+  parameters(type: Type): List<List<any>>;
+  annotations(type: Type): List<any>;
+  getter(name: string): GetterFn;
+  setter(name: string): SetterFn;
+  method(name: string): MethodFn;
+}