Make the dimension picker only accept highlighted values between (1,1) and (maxColumns, maxRows), inclusive. This makes interacting with it via keyboardand mouse more consistent. This also improves a11y for the component.
Also fixes a type warning in setValue().

R=nicksantos
DELTA=66 (33 added, 5 deleted, 28 changed)


Revision created by MOE tool push_codebase.
MOE_MIGRATION=6205


git-svn-id: http://closure-library.googlecode.com/svn/trunk@2472 0b95b8e8-c90f-11de-9d4f-f947ee5921c8