Make dijit/popup limit height (and add scrollbar) on the wrapper <div>, in order to fit popup in viewport.  Previously this functionality was in _HasDropDown, which was adding a scrollbar on the popup itself, but that doesn't work for Menus because they are <table>'s, and <table>'s can't have scrollbars.   The alternate approach would be to add wrapper <div>'s to all Menu's, like !SelectMenu used to do before this check in.

A complication from putting the scrollbar on the wrapper <div> was that I needed to add code to move the border from the popup widget to the wrapper, so that the scrollbar is inside the border.

Simplified !SelectMenu class to not create an extra <div>; it's no longer needed.  Note that !SelectMenu is still overcomplicated: there's no need for a <table> when you only have one column.

Finally, to avoid the "double border problem" where the popup meets the aroundNode, changed dijit/place to adjust the popup and aroundNode border to overlap, assuming both have borders.   Previously the double border was handled for drop down Menus in claro with a margin: -1px setting on the Menu.   But that technique no longer works.   Also, the double border problem wasn't being handled in other cases, like other themes and the drop down !ColorPalette in test_Button.html.

Fixes #10631 !strict.