Fix clipping wrapped Button text

Fixes two issues
1) We don't want the button base line aligned
2) Height of larger button shouldn't be constrained to the
 size of the smaller button. By default, this is true
 unless weight applies to height. But on sprout
 devices this doesn't happen inside AlertDialogs (this
 works properly on Hammerhead, even if I make the
 text long enough to force text wrap). I work around
 this by using measureWithLargestChild. The bug is
 so subtle, that I'm not going to bother wasting
 time convincing the framework team this is a bug,
 or looking into this deeper.

Bug: 18251517
Change-Id: Ia6eeedf6ed6eeddcd3946902705c74724c6c2329