Incorrect behavior for signTransaction function

[Senshii]

Description

Hello,
I use web3 offline without a node connection. I have a problem with the signTransaction method (web3.eth.accounts.signTransaction). Nonce existence check in this method is not correct.

Expected behavior

Calling web3.eth.accounts.signTransaction with a nonce (even at 0) should return a signed transaction without trying to call the ethereum node.

Actual behavior

Calling web3.eth.accounts.signTransaction with a nonce at 0 will call the ethereum node to get the transactionCount

Steps to reproduce the behavior

1. Import `web3`
2. Try to sign a transaction like this:

     web3.eth.accounts
       .signTransaction(
         {
           gas: 1000000,
           nonce: 0,
           chainId,
           gasPrice,
           data,
         },
         account.privateKey,
       )

3. You can see that your node is called with

{ jsonrpc: '2.0',
id: 1,
method: 'eth_getTransactionCount',
params: [ 'Address', 'latest' ] }

Versions

• web3.js: 1.0.0-beta.52
• nodejs: 10.15.3

I think the problem is at this line: https://github.com/ethereum/web3.js/blob/1.0/packages/web3-eth-accounts/src/Accounts.js#L158
The if condition return false if nonce is set to 0.