Adding class SkDeferredCanvas for deferred rendering.

TEST=added a new pass to gm, so all gm tests are run through SkDeferredCanvas
REVIEW=http://codereview.appspot.com/5430058/



git-svn-id: http://skia.googlecode.com/svn/trunk@3059 2bbb7eff-a529-9590-31e7-b0007b416f81
6 files changed