Khan/khan-exercises — pull request #24635 by xymostech (2012-06-22 18:48:46+00:00)
Title: Ensure labels with no content are not MathJax'd

If a label has no content, still create it (in case it needs to be used later) but ensure that no MathJax is run on it, which might cause a [Math Processing Error] to be displayed

compare:
old: http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/congruent_triangles_2.html?nocache
new: http://sandcastle.khanacademy.org/media/castles/xymostech:fix-mathjax-errors/exercises/congruent_triangles_2.html?nocache

@spicyj @beneater review?