Make "have size" syntax require the Size type class everywhere.


git-svn-id: http://scalatest.googlecode.com/svn/trunk@5110 fd1274fd-080f-5963-8033-43ee40fcd1de
Consolidated two implicits.


git-svn-id: http://scalatest.googlecode.com/svn/trunk@5111 fd1274fd-080f-5963-8033-43ee40fcd1de