Add skia-wasm-release image.

This should let us pipe continuous builds into jsfiddle.skia.org and
skottie.skia.org

Bug: skia:
Change-Id: I587e1293237d42dfdacae0757f44634f29d6f251
Reviewed-on: https://skia-review.googlesource.com/c/168440
Reviewed-by: Joe Gregorio <jcgregorio@google.com>
4 files changed