refactor(signin): Extract unblock-code-checking into a separate helper function.
refactor(signin): Extract unblock-code-checking into a separate helper function.

eoger/fxa-auth-server,mozilla/fxa-auth-server,mozilla/fxa-auth-server,mozilla/fxa-auth-server,eoger/fxa-auth-server,eoger/fxa-auth-server,eoger/fxa-auth-server,mozilla/fxa-auth-server