chore(test): rename RootTestComponent to ComponentFixture

BREAKING CHANGE:

Before:

```
testComponentBuilder.createAsync(MyComponent).then(root: RootTestComponent => {
}
```

After:

```
testComponentBuilder.createAsync(MyComponent).then(fixture: ComponentFixture => {
}
```

Closes #4711

modules/angular2/test/core/linker/dynamic_component_loader_spec.ts

@@ -13,7 +13,7 @@ import {
   it,
   xit,
   TestComponentBuilder,
-  RootTestComponent
+  ComponentFixture
 } from 'angular2/testing_internal';
 
 import {OnDestroy} from 'angular2/lifecycle_hooks';
@@ -24,7 +24,7 @@ import {DynamicComponentLoader} from 'angular2/src/core/linker/dynamic_component
 import {ElementRef} from 'angular2/src/core/linker/element_ref';
 import {DOCUMENT} from 'angular2/src/core/render/render';
 import {DOM} from 'angular2/src/core/dom/dom_adapter';
-import {RootTestComponent_} from "angular2/src/testing/test_component_builder";
+import {ComponentFixture_} from "angular2/src/testing/test_component_builder";
 
 export function main() {
   describe('DynamicComponentLoader', function() {
@@ -232,7 +232,7 @@ export function main() {
                   DOM.appendChild(doc.body, rootEl);
                   loader.loadAsRoot(ChildComp, null, injector)
                       .then((componentRef) => {
-                        var el = new RootTestComponent_(componentRef);
+                        var el = new ComponentFixture_(componentRef);
                         expect(rootEl.parentNode).toBe(doc.body);
 
                         el.detectChanges();

modules/angular2/test/core/linker/projection_integration_spec.ts

@@ -15,7 +15,7 @@ import {
   containsRegexp,
   stringifyElement,
   TestComponentBuilder,
-  RootTestComponent,
+  ComponentFixture,
   fakeAsync,
   tick
 } from 'angular2/testing_internal';
@@ -293,7 +293,7 @@ export function main() {
                     {template: '<simple string-prop="text"></simple>', directives: [Simple]}))
              .overrideTemplate(Simple, '<ng-content></ng-content><p>P,</p>{{stringProp}}')
              .createAsync(MainComp)
-             .then((main: RootTestComponent) => {
+             .then((main: ComponentFixture) => {
 
                main.detectChanges();
 
@@ -314,7 +314,7 @@ export function main() {
                     {template: '<simple string-prop="text"></simple>', directives: [Simple]}))
              .overrideTemplate(Simple, '<style></style><p>P,</p>{{stringProp}}')
              .createAsync(MainComp)
-             .then((main: RootTestComponent) => {
+             .then((main: ComponentFixture) => {
 
                main.detectChanges();
                expect(main.debugElement.nativeElement).toHaveText('P,text');

modules/angular2/test/core/linker/query_integration_spec.ts

@@ -211,10 +211,10 @@ export function main() {
 
            tcb.overrideTemplate(MyComp, template)
                .createAsync(MyComp)
-               .then((rtc) => {
-                 rtc.debugElement.componentInstance.shouldShow = true;
-                 rtc.detectChanges();
-                 rtc.destroy();
+               .then((fixture) => {
+                 fixture.debugElement.componentInstance.shouldShow = true;
+                 fixture.detectChanges();
+                 fixture.destroy();
 
                  async.done();
                });