Fix IE 11 detection.

IE 11 detection is broken on Mootools. This fix is based on
https://github.com/dez87/mootools-core/commit/c5c2e178665f1514d7f21ceb2c7671388c017d1a
with a minor tweak for proper version detection.
Merge pull request #4 from JPablomr/master

Fix IE 11 detection.