Use JavaScript in tests opening modal dialogs

This way we reproduce the user experience in the tests, and we can make
sure modal dialogs open when we expect it.

spec/system/debates_spec.rb

@@ -772,33 +772,31 @@ describe "Debates" do
     end
   end
 
-  scenario "Mark/Unmark a debate as featured", :admin do
+  scenario "Mark/Unmark a debate as featured", :admin, :js do
     debate = create(:debate)
 
     visit debates_path
     within("#debates") do
-      expect(page).not_to have_content "Featured"
+      expect(page).not_to have_content "FEATURED"
     end
 
     click_link debate.title
-
-    click_link "Featured"
-
-    visit debates_path
+    accept_confirm { click_link "Featured" }
 
     within("#debates") do
-      expect(page).to have_content "Featured"
+      expect(page).to have_content "FEATURED"
     end
 
     within("#featured-debates") do
       expect(page).to have_content debate.title
+
+      click_link debate.title
     end
 
-    visit debate_path(debate)
-    click_link "Unmark featured"
+    accept_confirm { click_link "Unmark featured" }
 
     within("#debates") do
-      expect(page).not_to have_content "Featured"
+      expect(page).not_to have_content "FEATURED"
     end
   end