The generated snapshot just crashes on the device, but
disabling snapshots allows us to run V8 just fine which
is sufficient for our purposes at this point.

Mojo/Sky are GN-only so we depend on the V8 GN build even if
it's not considered production for Chromium yet.

R=jochen@chromium.org

Review URL: https://codereview.chromium.org/832413005

Cr-Commit-Position: refs/heads/master@{#25982}