spec: 927147 block linked page from redirecting parent page

- verifies that the linked page cannot exploit the
Windows Opener Property bug
- verifies the link includes the rel="noreferrer" attribute
- turns out this was much more testable from Selenium
- no outside websites visited

Change-Id: I24ecb131c4eb4fd3528456c1aef79273a742ae96
Reviewed-on: https://gerrit.instructure.com/86406
Tested-by: Jenkins
Reviewed-by: August Thornton <august@instructure.com>
Reviewed-by: Gentry Beckmann <gbeckmann@instructure.com>
Product-Review: Gentry Beckmann <gbeckmann@instructure.com>
QA-Review: Gentry Beckmann <gbeckmann@instructure.com>

spec/selenium/wiki_pages_spec.rb

@@ -96,6 +96,13 @@ describe "Wiki Pages" do
       switch_editor_views(wiki_page_body)
       expect(f('textarea')).to include_text('test')
     end
+
+    it "blocks linked page from redirecting parent page", priority: "2", test_id: 927147 do
+      @course.wiki.wiki_pages.create!(title: 'Garfield and Odie Food Preparation',
+        body: '<a href="http://example.com/poc/" target="_blank" id="click_here_now">click_here</a>')
+      get "/courses/#{@course.id}/pages/garfield-and-odie-food-preparation"
+      expect(f('#click_here_now').attribute("rel")).to eq "noreferrer"
+    end
   end
 
   context "Index Page as a teacher" do