feat(di): support type literals in DI

modules/angular2/src/di/key.ts

@@ -1,5 +1,8 @@
 import {MapWrapper} from 'angular2/src/facade/collection';
-import {stringify} from 'angular2/src/facade/lang';
+import {stringify, CONST, Type} from 'angular2/src/facade/lang';
+import {TypeLiteral} from './type_literal';
+
+export {TypeLiteral} from './type_literal';
 
 // TODO: uncoment `int` once https://github.com/angular/angular/issues/1414 is fixed
 
@@ -18,6 +21,10 @@ import {stringify} from 'angular2/src/facade/lang';
 export class Key {
   token: Object;
   id: number;
+
+  /**
+   * @private
+   */
   constructor(token: Object, id: number) {
     this.token = token;
     this.id = id;
@@ -46,6 +53,13 @@ export class KeyRegistry {
   get(token: Object): Key {
     if (token instanceof Key) return token;
 
+    // TODO: workaround for https://github.com/Microsoft/TypeScript/issues/3123
+    var theToken = token;
+    if (token instanceof TypeLiteral) {
+      theToken = token.type;
+    }
+    token = theToken;
+
     if (MapWrapper.contains(this._allKeys, token)) {
       return MapWrapper.get(this._allKeys, token);
     }

modules/angular2/src/di/type_literal.dart

@@ -0,0 +1,26 @@
+library angular2.di.type_literal;
+
+/**
+ * Use type literals as DI keys corresponding to generic types.
+ *
+ * Example:
+ *
+ * ```
+ * Injector.resolveAndCreate([
+ *   bind(new TypeLiteral<List<int>>()).toValue([1, 2, 3])
+ * ]);
+ *
+ * class Foo {
+ *   // Delend on `List<int>` normally.
+ *   Foo(List<int> list) { ... }
+ * }
+ * ```
+ *
+ * This capability might be added to the language one day. See:
+ *
+ * https://code.google.com/p/dart/issues/detail?id=11923
+ */
+class TypeLiteral<T> {
+  const TypeLiteral();
+  Type get type => T;
+}

modules/angular2/src/di/type_literal.ts

@@ -0,0 +1,7 @@
+/**
+ * Type literals is a Dart-only feature. This is here only so we can x-compile
+ * to multiple languages.
+ */
+export class TypeLiteral {
+  get type(): any { throw new Error("Type literals are only supported in Dart"); }
+}