rename SkDeque::Iter to SkDeque::F2BIter, since it runs front-to-back (in preparation
for another iter that runs back-to-front (B2FIter).

add unittest for Deque



git-svn-id: http://skia.googlecode.com/svn/trunk@821 2bbb7eff-a529-9590-31e7-b0007b416f81
6 files changed