Don't use mock PagePopup if possible.

Update some tests in fast/forms/{calendar-picker,color,page-popup}/
so that they use openPicker() instead of openPickerWithMock().

BUG=409503

Review URL: https://codereview.chromium.org/629103002

git-svn-id: svn://svn.chromium.org/blink/trunk@183249 bbb929c8-8fbe-4397-9dbb-9b2b20218538