Add legacy++ to viewer (sRGB w/nonlinear blending)

BUG=skia:6242

Change-Id: I696de8eac61aebaf5cb07d8874bde3c7bd470277
Reviewed-on: https://skia-review.googlesource.com/9299
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>
2 files changed