Adding Angular and dependent packages for testing

third_party/pkg/angular/test/directive/ng_show_hide_spec.dart

+library ng_show_hide_spec;
+
+import '../_specs.dart';
+
+
+main() {
+  describe('NgHide', () {
+    TestBed _;
+    beforeEach(inject((TestBed tb) => _ = tb));
+
+    it('should add/remove ng-hide class', () {
+      _.compile('<div ng-hide="isHidden"></div>');
+
+      expect(_.rootElement).not.toHaveClass('ng-hide');
+
+      _.rootScope.$apply(() {
+        _.rootScope['isHidden'] = true;
+      });
+      expect(_.rootElement).toHaveClass('ng-hide');
+
+      _.rootScope.$apply(() {
+        _.rootScope['isHidden'] = false;
+      });
+      expect(_.rootElement).not.toHaveClass('ng-hide');
+    });
+  });
+}