Fix #4931: Add popup voter list for comments.

Show the comment's upvote and downvote count when you hover over a
comment's score. For mods, show the list of voters as well.

test/functional/comment_votes_controller_test.rb

@@ -27,6 +27,11 @@ class CommentVotesControllerTest < ActionDispatch::IntegrationTest
           assert_response :success
         end
 
+        should "render for a tooltip" do
+          get comment_votes_path(comment_id: @comment.id, variant: "tooltip")
+          assert_response :success
+        end
+
         should respond_to_search({}).with { [] }
       end
 
@@ -35,6 +40,11 @@ class CommentVotesControllerTest < ActionDispatch::IntegrationTest
           CurrentUser.user = create(:mod_user)
         end
 
+        should "render for a tooltip" do
+          get comment_votes_path(comment_id: @comment.id, variant: "tooltip")
+          assert_response :success
+        end
+
         should respond_to_search({}).with { [@unrelated_vote, @negative_vote, @vote] }
         should respond_to_search(score: -1).with { @negative_vote }