[CommonHTML] elements with font specified are not properly scaled

Specifying a font-family in CommonHTML causes the element to be scaled improperly.  E.g.

```
\style{font-family:inherit}{x}
\unicode[Arial]{xE0}
\mmlToken{mi}[fontfamily="Arial"]{x}
```

all cause the elements to be scaled when compared to the math font.  This is not the case for HTML-CSS and SVG output.
