remove a console error in the reployed version

Cleanup to the deploy process:
- create an empty user.json file; this prevents an error from being written into the console when the deployed app starts up
- remove a workaround for a `smoke` issue; no longer necesary
- removed an unused `deployForDartium` task

@dinhviethoa
@dinhviethoa, dp you know if we still need this?