Work around jsdom error that doesn't set width and height of span elements.
Work around jsdom error that doesn't set width and height of span elements.

benetech/MathJax-node,wikimedia/MathJax-node,episodeyang/MathJax-node,ghostxt/MathJax-node,physikerwelt/MathJax-node,episodeyang/MathJax-node,rachetfoot/MathJax-rhino,mathjax/MathJax-node,wikimedia/MathJax-node,pkra/MathJax-node,benetech/MathJax-node,rachetfoot/MathJax-rhino,rachetfoot/MathJax-rhino,ghostxt/MathJax-node,physikerwelt/MathJax-node