added support for sk_Dimensions to SkSL

Bug: skia:
Change-Id: I5f6a9941822b7b4a3ad85b22b1bcd31d58320f90
Reviewed-on: https://skia-review.googlesource.com/146640
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
23 files changed