chore: add testing API back

Author: Foxandxss

tools/api-builder/angular.io-package/index.js

@@ -59,26 +59,29 @@ module.exports = new Package('angular.io', [basePackage, targetPackage, cheatshe
     '___core_private_testing_types__',
     '___compiler_private__',
     '__core_private__',
-    '___core_private__'
+    '___core_private__',
+    '___core_private_testing_placeholder__',
+    '___core_private_testing__'
   ];
 
   readTypeScriptModules.sourceFiles = [
     '@angular/common/index.ts',
-    '@angular/common/testing.ts',
+    '@angular/common/testing/index.ts',
     '@angular/core/index.ts',
-    '@angular/core/testing.ts',
+    '@angular/core/testing/index.ts',
     '@angular/forms/index.ts',
     '@angular/http/index.ts',
-    '@angular/http/testing.ts',
+    '@angular/http/testing/index.ts',
     '@angular/platform-browser/index.ts',
-    '@angular/platform-browser/testing.ts',
+    '@angular/platform-browser/testing/index.ts',
     '@angular/platform-browser-dynamic/index.ts',
-    '@angular/platform-browser-dynamic/testing.ts',
+    '@angular/platform-browser-dynamic/testing/index.ts',
     '@angular/platform-server/index.ts',
-    '@angular/platform-server/testing.ts',
+    '@angular/platform-server/testing/index.ts',
     '@angular/platform-webworker/index.ts',
     '@angular/platform-webworker-dynamic/index.ts',
     '@angular/router/index.ts',
+    '@angular/router/testing/index.ts',
     '@angular/router-deprecated/index.ts',
     '@angular/upgrade/index.ts',
   ];