fix(bug): reflect Dart interfaces from superclass as well

fixes angular#4221

Closes angular#4222

Author: alexeagle

modules/angular2/src/core/reflection/reflection_capabilities.dart

@@ -272,8 +272,13 @@ class ReflectionCapabilities implements PlatformReflectionCapabilities {
   }
 
   List interfaces(type) {
-    ClassMirror classMirror = reflectType(type);
-    return classMirror.superinterfaces.map((si) => si.reflectedType).toList();
+    return _interfacesFromMirror(reflectType(type));
+  }
+
+  List _interfacesFromMirror(classMirror) {
+    return classMirror.superinterfaces.map((si) => si.reflectedType).toList()
+      ..addAll(classMirror.superclass == null ? []
+        : _interfacesFromMirror(classMirror.superclass));
   }
 
   GetterFn getter(String name) {

modules/angular2/test/core/reflection/reflector_spec.ts

@@ -51,7 +51,11 @@ class TestObj {
 
 class Interface {}
 
-class ClassImplementingInterface implements Interface {}
+class Interface2 {}
+
+class SuperClassImplementingInterface implements Interface2 {}
+
+class ClassImplementingInterface extends SuperClassImplementingInterface implements Interface {}
 
 export function main() {
   describe('Reflector', () => {
@@ -191,7 +195,7 @@ export function main() {
       describe("interfaces", () => {
         it("should return an array of interfaces for a type", () => {
           var p = reflector.interfaces(ClassImplementingInterface);
-          expect(p).toEqual([Interface]);
+          expect(p).toEqual([Interface, Interface2]);
         });
 
         it("should return an empty array otherwise", () => {