Only include SkJSONWriter when SK_ENABLE_DUMP_GPU defined

Also fix some missing includes in:
 - src/gpu/effects/GrPorterDuffXferProcessor.cpp
 - src/gpu/GrDirectContext.cpp
 - tools/DDLPromiseImageHelper.h

Change-Id: I1b30827e1442fd01534427b52549f8775300b365
Bug: skia:12584
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/466876
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
9 files changed