Get prop for signed typed data from domain instead of message

[danjm]

Fixes #7395

We were mistakenly looking for the user readable name of the message sender within the wrong property of the message data. The name is optionally available within the domain property, as detailed here: https://github.com/ethereum/EIPs/blob/master/EIPS/eip-712.md#definition-of-domainseparator

This updates the UI code to reflect that.

Ideally we should test this with a few use cases.

[danjm]

Tested with both the example data from the EIP and the data shared in this comment: #7395 (comment)

Tested both with v3 and v4 signing methods

[Gudahtt]

This looks correct to me!

[metamaskbot]

Builds ready [ef039d2]

• builds: chrome, firefox, opera, edge
• bundle viz: background, ui, inpage, contentscript, ui-libs, bg-libs, phishing-detect
• dep viz: background
• all artifacts

[danjm]

Also tested with the below example:

const types = [
  'address', // makerAddress
  'uint256', // makerAmount
  'address', // makerToken
  'address', // takerAddress
  'uint256', // takerAmount
  'address', // takertoken
  'uint256', // expiration
  'uint256', // nonce
]
const orderHash = ethers.utils.solidityKeccak256(
  types,
  [
    '0x3C393072dDefa188282449dF78c585847a17E589',
    1,
    '0xB22c1C159d12461EA124b0deb4b5b93020E6Ad16',
    '0x145f71b7a87a0EB88d1391f3D56D5ea92A26dF26',
    1,
    '0xb1690C08E213a35Ed9bAb7B318DE14420FB57d8C',
    1573653901352,
    10
  ]
)
const testOrderHash = "0x323a0630961846b7e0e9d1a453cc87caa5ca909cc890ac735a63b8d5ccbe7e21"
const domainData = {
  verifyingContract: "0xbcd24b757c08843010b94cda1f8d03b90b167301",
}
const order = [
  { name: "orderHash", type: "bytes32" },
]
const msg = {
  orderHash: testOrderHash
}
const data = {
  types: {
    Order: order,
    EIP712Domain: [
      { name: "verifyingContract", type: "bytes32"  },
    ],
  },
  domain: domainData,
  primaryType: "Order",
  message: msg,
}
const typedMessageJSON = JSON.stringify(data)
var params = [ethereum.selectedAddress, typedMessageJSON]
var method = 'eth_signTypedData_v3'

web3.currentProvider.sendAsync({
  method,
  params,
  from: ethereum.selectedAddress,
}, function(err, result) {
  if (err) return console.error(err)
  console.log(result)
})