feat(debug): replace DebugElement with new Debug DOM

Now, using `ng.probe(element)` in the browser console returns
a DebugElement when in dev mode.

`ComponentFixture#debugElement` also returns a new DebugElement.

Breaking Change:

This is a breaking change for unit tests. The API for the DebugElement
has changed. Now, there is a DebugElement or DebugNode for every node
in the DOM, not only nodes with an ElementRef. `componentViewChildren` is
removed, and `childNodes` is a list of ElementNodes corresponding to every
child in the DOM. `query` no longer takes a scope parameter, since
the entire rendered DOM is included in the `childNodes`.

Before:

```
componentFixture.debugElement.componentViewChildren[0];
```

After
```
// Depending on the DOM structure of your component, the
// index may have changed or the first component child
// may be a sub-child.
componentFixture.debugElement.children[0];
```

Before:

```
debugElement.query(By.css('div'), Scope.all());
```

After:

```
debugElement.query(By.css('div'));
```

Before:

```
componentFixture.debugElement.elementRef;
```

After:

```
componentFixture.elementRef;
```

modules/angular2/src/web_workers/worker/renderer.ts

@@ -1,4 +1,9 @@
-import {Renderer, RootRenderer, RenderComponentType} from 'angular2/src/core/render/api';
+import {
+  Renderer,
+  RootRenderer,
+  RenderComponentType,
+  RenderDebugInfo
+} from 'angular2/src/core/render/api';
 import {
   ClientMessageBroker,
   ClientMessageBrokerFactory,
@@ -186,6 +191,8 @@ export class WebWorkerRenderer implements Renderer, RenderStoreObject {
     ]);
   }
 
+  setElementDebugInfo(renderElement: any, info: RenderDebugInfo) {}
+
   setElementClass(renderElement: any, className: string, isAdd: boolean) {
     this._runOnService('setElementClass', [
       new FnArg(renderElement, RenderStoreObject),