Get position of overscript correct, and don't combine bboxes unnecessarily.
Get position of overscript correct, and don't combine bboxes unnecessarily.

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