[TeX] vcenter: SVG (and HTML-CSS) should match CommonHTML behavior
Via https://github.com/mathjax/MathJax/issues/1802#issuecomment-314244105
The CommonHTML output renders content following vcenter
incorrectly.
Minimal example $\vcenter{a\\b}y$
- the y
will be moved far to the right of the vcenter
content.