Make drawIndexedInstances non-virtual and rewrite GrIODB's drawRect on top of drawIndexedInstances.

R=robertphillips@google.com
Review URL: https://codereview.appspot.com/7221078

git-svn-id: http://skia.googlecode.com/svn/trunk@7508 2bbb7eff-a529-9590-31e7-b0007b416f81
9 files changed