fixed ArithmeticImageFilter input type

The recent change to SkSL input precisions was causing a problem in
ArithmeticImageFilter, where it specifies a half4 input (therefore
implying an SkPMColor) but the code actually passes a float[4] in.

Bug: skia:
Change-Id: Icbe4b60baeda9d0dad3946b1a64cb3e93d117f88
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/206204
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
Auto-Submit: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
1 file changed