makeFontSizer = function(options, fontSize) {
                    var fontSizeInner = makeSpan([], [new domTree.symbolNode("\u200b")]);
                    fontSizeInner.style.fontSize =
                        (fontSize / options.style.sizeMultiplier) + "em";

                    var fontSizer = makeSpan(
                        ["fontsize-ensurer", "reset-" + options.size, "size5"],
                        [fontSizeInner]);

                    return fontSizer;
                }
Maps TeX font commands to objects containing:
- variant: string used for "mathvariant" attribute in buildMathML.js
- fontName: the "style" parameter to fontMetrics.getCharacterMetrics