fix showing less than and greater than in code

common/static/coffee/src/discussion/views/discussion_thread_show_view.coffee

@@ -47,7 +47,7 @@ if Backbone?
 
     convertMath: ->
       element = @$(".post-body")
-      element.html DiscussionUtil.postMathJaxProcessor DiscussionUtil.markdownWithHighlight element.html()
+      element.html DiscussionUtil.postMathJaxProcessor DiscussionUtil.markdownWithHighlight element.text()
       MathJax.Hub.Queue ["Typeset", MathJax.Hub, element[0]]
 
     toggleVote: (event) ->