Revert "Revert "eliminated GrGLSLExpr""

This reverts commit 5e550ab57e0204bfadd2cb69c47d2a85e38d6a4c.

Bug: skia:
Change-Id: I4705e47dbd209aa8f43db3d28c856bd3aa9e49ab
Reviewed-on: https://skia-review.googlesource.com/15187
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
29 files changed