refactor(injector): use @CONST to create the Inject annotation

modules/di/src/annotations.js

@@ -1,7 +1,8 @@
-//TODO: vsavkin: uncomment once const constructor are supported
-//export class Inject {
-//  @CONST
-//  constructor(token){
-//    this.token = token;
-//  }
-//}
+import {CONST} from "facade/lang";
+
+export class Inject {
+  @CONST()
+  constructor(token){
+    this.token = token;
+  }
+}

modules/di/src/binding.js

@@ -1,6 +1,6 @@
 import {Type} from 'facade/lang';
 import {List, MapWrapper, ListWrapper} from 'facade/collection';
-import {Reflector} from 'facade/di/reflector';
+import {Reflector} from './reflector';
 import {Key} from './key';
 
 export class Binding {

modules/di/src/di.js

@@ -1,5 +1,5 @@
+export * from './annotations';
 export * from './injector';
 export * from './binding';
 export * from './key';
 export * from './module';
-export {Inject} from 'facade/di/reflector';

modules/di/src/reflector.dart

@@ -1,11 +1,7 @@
 library facade.di.reflector;
 
 import 'dart:mirrors';
-
-class Inject {
-  final Object token;
-  const Inject(this.token);
-}
+import 'annotations.dart' show Inject;
 
 class Reflector {
   factoryFor(Type type) {

modules/di/src/reflector.es6

@@ -1,11 +1,5 @@
 import {Type} from 'facade/lang';
-
-//TODO: vsvakin: remove when const constructors are implemented
-export class Inject {
-  constructor(token){
-    this.token = token;
-  }
-}
+import {Inject} from './annotations';
 
 export class Reflector {
   factoryFor(type:Type) {