I poked around and they’re creating that text as a VML shape in typeface-0.14.js.
In typeface-0.14.js they’re doing this check to determine whether to use canvas or VML for the text in question:
var backend = !!(window.attachEvent && !window.opera) ? 'vml' : window.CanvasRenderingContext2D || document.createElement('canvas').getContext ? 'canvas' : null;
Since IE9 is returning a function for window.attachEvent, it’s using VML as the rendering backend instead of canvas. Really they should be doing the check in the middle (for canvas features) first, I’d think…
Anyway, the VML rendering path for the page has this suspect line when creating text: shape.style.flip = 'y';
This line seems to have no effect in IE9. I can’t speak to why because I’m not too familiar with VML, but it’s why the text is upside-down.
I suspect this is related:
http://msdn.microsoft.com/en-us/library/gg622932(v=VS.85).aspx
The solution would probably be to reach out to them about using canvas for their text rendering solution in IE9, or to add a meta tag to force IE8 mode. I tinkered around with Fiddler a bit to coax the page into using canvas and it works fine that way.