fix for uninitialized GrGLSLFragmentShaderBuilder field

Bug: skia:
Change-Id: I5041c96528910d24978a5c2578efa29d6a89a343
Reviewed-on: https://skia-review.googlesource.com/46982
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Stephan Altmueller <stephana@google.com>
Reviewed-by: Stephan Altmueller <stephana@google.com>
1 file changed