build(broccoli): AngularBuilder compiles with TypeScript 1.8+.

Beginning with 1.8, if a modules has both a .ts and .d.ts file, the .js
file is not written.

Closes #7947

tools/broccoli/angular_builder.d.ts

@@ -1,5 +0,0 @@
-interface AngularBuilderOptions {
-  outputPath: string;
-  dartSDK?: any;
-  logs?: any;
-}

tools/broccoli/angular_builder.ts

@@ -17,6 +17,12 @@ export type Options = {
   useBundles: boolean;
 };
 
+export interface AngularBuilderOptions {
+  outputPath: string;
+  dartSDK?: any;
+  logs?: any;
+}
+
 /**
  * BroccoliBuilder facade for all of our build pipelines.
  */

tools/broccoli/trees/dart_tree.ts

@@ -1,5 +1,4 @@
 /// <reference path="../../typings/node/node.d.ts" />
-/// <reference path="../angular_builder.d.ts" />
 'use strict';
 
 import {MultiCopy} from './../multi_copy';
@@ -12,6 +11,7 @@ var stew = require('broccoli-stew');
 import ts2dart from '../broccoli-ts2dart';
 import dartfmt from '../broccoli-dartfmt';
 import replace from '../broccoli-replace';
+import {AngularBuilderOptions} from '../angular_builder';
 
 var global_excludes = [
   'angular2/examples/**/ts/**/*',