Firefox update changed behaviour of the selenium tests, it is not
enough to click on the div representing dropdown menu region,
one must click on the first child (which is now button, but i suppose
it can change over time to input or anything else) in order to open the
dropdown menu.
Closes-Bug: #1399268
Partially implements blueprint: selenium-integration-testing
Change-Id: If9aed4b547f843d16ba729f84cb2c02acb2a0a4d