Don't use mock PagePopup if possible, part 2

Update some tests in fast/forms/suggestion-picker/ so that they use
openPicker() instead of openPickerWithMock().

BUG=409503

Review URL: https://codereview.chromium.org/633823003

git-svn-id: svn://svn.chromium.org/blink/trunk@183720 bbb929c8-8fbe-4397-9dbb-9b2b20218538