Fix client-side contentUrl to avoid invariant error
Fix client-side contentUrl to avoid invariant error

fzzzy/pageshot,fzzzy/pageshot,mozilla-services/pageshot,mozilla-services/screenshots,mozilla-services/pageshot,mozilla-services/screenshots,mozilla-services/screenshots,fzzzy/pageshot,mozilla-services/pageshot,fzzzy/pageshot,mozilla-services/screenshots,mozilla-services/pageshot