Clamp gradient colors in fragment shader after interpolation when there is a color space.

This matches what is done in the LUT texture case.

Change-Id: I95ab8c9ac761a3315a55a7f81bfe2e4077070542
Reviewed-on: https://skia-review.googlesource.com/8813
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
1 file changed