Make GrDrawTarget::Caps ref counted and GrGLCaps derive from it.

Also rename GrDrawTarget::getCaps() -> GrDrawTarget::caps().
Review URL: https://codereview.chromium.org/12843026

git-svn-id: http://skia.googlecode.com/svn/trunk@8364 2bbb7eff-a529-9590-31e7-b0007b416f81
22 files changed