IE10 compatibility: no tooltip on icon.html example

How to reproduce:
 * Open IE10 on Win7 without touch
 * Load http://ol3js.org/en/master/examples/icon.html
 * click on the icon
 * nothing happens

Expected
 * Open IE10 on Win7 without touch
 * Load http://ol3js.org/en/master/examples/icon.html
 * Click on the icon
 * A tooltip displaying "Null Island" appears

Note:
 * Does work on chrome