FIX: Ignore group mentions inside quotes (#8905)

Also includes:
* DEV: Reuse found elements

app/models/post_analyzer.rb

@@ -132,7 +132,7 @@ class PostAnalyzer
   def cooked_stripped
     @cooked_stripped ||= begin
       doc = Nokogiri::HTML.fragment(cook(@raw, topic_id: @topic_id))
-      doc.css("pre .mention, aside.quote > .title, aside.quote .mention, .onebox, .elided").remove
+      doc.css("pre .mention, aside.quote > .title, aside.quote .mention, aside.quote .mention-group, .onebox, .elided").remove
       doc
     end
   end

lib/pretty_text.rb

@@ -447,7 +447,7 @@ module PrettyText
 
     mentions = lookup_mentions(names, user_id: user_id)
 
-    doc.css("span.mention").each do |element|
+    elements.each do |element|
       name = element.text[1..-1]
       name.downcase!
 

spec/models/post_analyzer_spec.rb

@@ -236,6 +236,13 @@ describe PostAnalyzer do
       expect(post_analyzer.raw_mentions).to eq(['finn'])
     end
 
+    it "ignores group mentions in quotes" do
+      Fabricate(:group, name: "team")
+      Fabricate(:group, name: "mods")
+      post_analyzer = PostAnalyzer.new("[quote=\"Evil Trout\"]\n@team\n[/quote]\n @mods", default_topic_id)
+      expect(post_analyzer.raw_mentions).to eq(["mods"])
+    end
+
     it "ignores oneboxes" do
       post_analyzer = PostAnalyzer.new("Hello @Jake\n#{url}", default_topic_id)
       post_analyzer.stubs(:cook).returns("<p>Hello <span class=\"mention\">@Jake</span><br><a href=\"https://twitter.com/evil_trout/status/345954894420787200\" class=\"onebox\" target=\"_blank\" rel=\"nofollow noopener\">@Finn</a></p>")