allow arbitrary Builder Features

Should allow us to test sksl->skvm portably using dump().

Change-Id: If55e8e144f04643c02bd65baa84158ac1bf441b5
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/346336
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
3 files changed