Improved user experience for drop down widgets on touch devices

Before this PR, when selecting an item in the popup of a drop down widget (such as a DatePicker, an AutoComplete, a SelectBox or a MultiSelect), the focus goes back to the input element.

On touch devices, focusing an input element triggers the display of the keyboard. This PR prevents the focus from going back to the input element immediately after selecting an element in the popup of a drop down widget on touch devices or when touching the dropdown icon.

The behavior is not changed on non-touch devices (the detection of touch devices is done through `aria.utils.Device.isTouch`).
The name is misleading. Inside this function, you perform two steps: 

- waiting for the popup and then clicking on the input
- waiting for the popup to disappear and checking the focus

Those two equivalent steps are clearly separated in `case*Popup` cases, but here they are not. This is a bit confusing, especially since the name of the method reflects only the first step. When reading the test cases using it, we wonder at first sight if/when the focus is actually checked.

Either we split it to match the design of the other test cases, or we rename it, despite the resulting really long name: `waitForPopupAndClickOnInputAndWaitForNoPopupAndCheckFocus`... I would go for the first solution :p