Move SkTDStackNester into its own private file.

Also remove depth(), which is unused.

Otherwise the class is unchanged.

R=mtklein@google.com

Review URL: https://codereview.chromium.org/64093009

git-svn-id: http://skia.googlecode.com/svn/trunk@12324 2bbb7eff-a529-9590-31e7-b0007b416f81
3 files changed