Round em's to nearest pixel to avoid WebKit alignment issues.  Resolves issue #1283.
Round em's to nearest pixel to avoid WebKit alignment issues.  Resolves issue #1283.

thomasjm/MathJax,thomasjm/MathJax,jinntrance/mathjax,thomasjm/MathJax,dpvc/MathJax,GerHobbelt/MathJax,jinntrance/mathjax,wikimedia/MathJax,GerHobbelt/MathJax,thomasjm/MathJax,thomasjm/MathJax