Problem when media query changes vw to em in font-size in IE9+

[celiolatorraca]

Hi,

I've got a problem when adding a media query that changes font-size of an element from vw to em, when using IE 9+.
It keeps calculating conversion between them of the previous value (vw in this case), so the newer one (em) doesn't work properly...

I've created an example that reproduces the problem...
http://jsfiddle.net/celio_latorraca/ekvbycdx/6/

You just need to access JS Fiddle with IE and resize the iframe to see what happens.
To facilitate debugging, it's changing color between blue and red when media query changes...
So, to understand the problem, when the font color is red, the font-size is in em and don't changes with window resize... But, when it is blue, it follows the resizing.

Thanks!

[rodneyrehm]

duplicate of #52, #13