In GrSkSLFP, advance the iterator pointer while building the key

We were checking the flags for each uniform, but never advancing the
uniform iterator. As a result, for each uniform that was specialized,
we'd just fold in another copy of the *first* uniform's data.

This led to a nasty performance regression (extra shader compiles) in
certain scenarios. (And it was a correctness issue, as well).

Change-Id: Iaac878a7b9eb37e98815f56dc55a58d1f8e85c22
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/420820
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
1 file changed