FAPI

Drupal 7 FAPI's #states: Take care of Internet Explorer (IE)!!! (Conditional fields not working in IE)

Today I ran into a very very mad bug: conditional_fields.module did not correctly work in IE, as discussed in this issue:
https://www.drupal.org/node/1373656

But as I later found out and posted here this problem is based on the FAPI #states API!