Adding Angular and dependent packages for testing

third_party/pkg/angular/lib/directive/ng_a.dart

+part of angular.directive;
+
+/**
+ * @ngdoc directive
+ * @name ng.directive:a
+ * @restrict E
+ *
+ * @description
+ * Modifies the default behavior of the html A tag so that the default action is prevented when
+ * the href attribute is empty.
+ *
+ * This change permits the easy creation of action links with the `ngClick` directive
+ * without changing the location or causing page reloads, e.g.:
+ * `<a href="" ng-click="model.$save()">Save</a>`
+ */
+@NgDirective(selector: 'a[href]')
+class NgADirective {
+  dom.Element element;
+
+  NgADirective(dom.Element element) {
+    if (element.attributes["href"] == "") {
+      element.onClick.listen((event) {
+        if (element.attributes["href"] == "") {
+          event.preventDefault();
+        }
+      });
+    }
+  }
+}