Prevent default behaviour on arrow up/down in SuggestBox.

Change-Id: Icf311f65106ebd62b612a20fb9c383706e18aa33
Review-Link: https://gwt-review.googlesource.com/#/c/9998/
Remove broken j.u.logging sample

Logging works out of the box now so a complex sample app is not
much useful for most users.

Bug: issue 8971
Change-Id: I037bb9a551f9e5f1ead0cddc0f25578da894e293