refactor(testing): move common testing logic into test_injector

Before, all test framework wrappers (internal for dart and js/ts,
angular2_test for dart and testing for js/ts) had similar logic to
keep track of current global test injector and test provider list.
This change wraps that logic into one class managed by the test
injector.

Closes #5920

modules/angular2/test/web_workers/debug_tools/multi_client_server_message_bus.server.spec.dart

@@ -11,7 +11,6 @@ import "package:angular2/testing_internal.dart"
         iit,
         expect,
         beforeEach,
-        createTestInjector,
         beforeEachProviders,
         SpyObject,
         proxy;

modules/angular2/test/web_workers/debug_tools/single_client_server_message_bus.server.spec.dart

@@ -10,7 +10,6 @@ import "package:angular2/testing_internal.dart"
         it,
         expect,
         beforeEach,
-        createTestInjector,
         beforeEachProviders,
         SpyObject,
         proxy;

modules/angular2/test/web_workers/debug_tools/web_socket_message_bus_spec.dart

@@ -8,7 +8,6 @@ import "package:angular2/testing_internal.dart"
         it,
         expect,
         beforeEach,
-        createTestInjector,
         beforeEachProviders,
         SpyObject,
         proxy;

modules/angular2/test/web_workers/shared/message_bus_spec.ts

@@ -5,7 +5,6 @@ import {
   it,
   expect,
   beforeEach,
-  createTestInjectorWithRuntimeCompiler,
   beforeEachProviders,
   SpyObject,
   proxy

modules/angular2/test/web_workers/shared/service_message_broker_spec.ts

@@ -5,7 +5,6 @@ import {
   it,
   expect,
   beforeEach,
-  createTestInjectorWithRuntimeCompiler,
   beforeEachProviders,
   SpyObject,
   proxy

modules/angular2/test/web_workers/worker/event_dispatcher_spec.ts

@@ -5,7 +5,6 @@ import {
   it,
   expect,
   beforeEach,
-  createTestInjectorWithRuntimeCompiler,
   beforeEachProviders,
   SpyObject,
   proxy

modules/angular2/test/web_workers/worker/renderer_integration_spec.ts

@@ -7,8 +7,8 @@ import {
   iit,
   expect,
   beforeEach,
-  createTestInjectorWithRuntimeCompiler,
   beforeEachProviders,
+  TestInjector,
   TestComponentBuilder
 } from "angular2/testing_internal";
 import {DOM} from 'angular2/src/platform/dom/dom_adapter';
@@ -102,12 +102,14 @@ export function main() {
     beforeEachProviders(() => {
       var uiRenderProtoViewStore = new RenderProtoViewRefStore(false);
       uiRenderViewStore = new RenderViewWithFragmentsStore(false);
-      uiInjector = createTestInjectorWithRuntimeCompiler([
+      var testInjector = new TestInjector();
+      testInjector.addProviders([
         provide(RenderProtoViewRefStore, {useValue: uiRenderProtoViewStore}),
         provide(RenderViewWithFragmentsStore, {useValue: uiRenderViewStore}),
         provide(DomRenderer, {useClass: DomRenderer_}),
         provide(Renderer, {useExisting: DomRenderer})
       ]);
+      uiInjector = testInjector.createInjector();
       var uiSerializer = uiInjector.get(Serializer);
       var domRenderer = uiInjector.get(DomRenderer);
       var workerRenderProtoViewStore = new RenderProtoViewRefStore(true);

modules/angular2/test/web_workers/worker/xhr_impl_spec.ts

@@ -5,7 +5,6 @@ import {
   it,
   expect,
   beforeEach,
-  createTestInjectorWithRuntimeCompiler,
   beforeEachProviders
 } from 'angular2/testing_internal';
 import {SpyMessageBroker} from './spies';