hide via-svg until I can fix g3

BUG=skia:

Change-Id: I226194a4db5c9618dd312337bf196d8f21825a12
Reviewed-on: https://skia-review.googlesource.com/8720
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
3 files changed