refactor(render): add DomElement

Replaces the multiple arrays of `DomView`
by a single array with `DomElement`s.

Note: this commit does not show a performance regression
(tested against the tree benchmark locally).

modules/angular2/src/core/application.ts

@@ -80,7 +80,7 @@ function _injectorBindings(appComponentType): List<Type | Binding | List<any>> {
                     var domView = resolveInternalDomView(componentRef.hostView.render);
                     // We need to do this here to ensure that we create Testability and
                     // it's ready on the window for users.
-                    registry.registerApplication(domView.boundElements[0], testability);
+                    registry.registerApplication(domView.boundElements[0].element, testability);
 
                     return componentRef;
                   });

modules/angular2/src/core/compiler/element_ref.ts

@@ -23,7 +23,9 @@ export class ElementRef {
   // We need a more general way to read/write to the DOM element
   // via a proper abstraction in the render layer
   get domElement() {
-    return resolveInternalDomView(this.parentView.render).boundElements[this.boundElementIndex];
+    return resolveInternalDomView(this.parentView.render)
+        .boundElements[this.boundElementIndex]
+        .element;
   }
 
   /**