Update the Angular/DI tests to latest from github.

third_party/pkg/angular/lib/mock/probe.dart

Index: third_party/pkg/angular/lib/mock/probe.dart
diff --git a/third_party/pkg/angular/lib/mock/probe.dart b/third_party/pkg/angular/lib/mock/probe.dart
index b146bf63d5c9d5e72129974395727b59a8278b8b..678e3cfcce058ebc111f669e87c1599355770300 100644
--- a/third_party/pkg/angular/lib/mock/probe.dart
+++ b/third_party/pkg/angular/lib/mock/probe.dart
@@ -17,10 +17,12 @@ class Probe implements NgDetachAware {
   final NodeAttrs _attrs;
 
   Probe(this.scope, this.injector, this.element, this._attrs) {
-    scope.$root[_attrs['probe']] = this;
+    scope.rootScope.context[_attrs['probe']] = this;
   }
 
-  detach() => scope.$root[_attrs['probe']] = null;
+  void detach() {
+    scope.rootScope.context[_attrs['probe']] = null;
+  }
 
   /**
    * Retrieve a Directive at the current element.