removed textureProj() and legacy texture functions from sksl

BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=5120

Change-Id: I21b111d54becaca845134376e54a5a7c0a6cd6c8
Reviewed-on: https://skia-review.googlesource.com/5120
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
11 files changed