height-constrained would not find an ideal width after just 10 iterations.
Changed it such that if the height constraint causes us to be layed
out in one line, we don't attempt the more complex height-constrained layout,
but instead just fall down to the one-line layout code.
git-svn-id: https://samskivert.googlecode.com/svn/trunk@798 6335cc39-0255-0410-8fd6-9bcaacd3b74c