Allow zero-pass to wallets in Development mode.

I'm Solidity developer and Metamask user. I think that it's may be helpfull to allow auto-unlock wallet in special Development mode.
Maybe allow it only for testnet AND enabled Developer mode ?

Review the MetaMask extension's Development mode and wallet unlock behavior, then clarify whether auto-unlock should be restricted to testnets and explicitly enabled developer mode. Done requires an agreed security scope and verified behavior for the selected conditions; the issue names no files or tests, so locate those entry points first.

Written by the indexing model from the issue text.