fixes defaultBlock property handling

[nivida]

Description

Fixes #3244

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• I have selected the correct base branch.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• Any dependent changes have been merged and published in downstream modules.
• I ran npm run dtslint with success and extended the tests and types if necessary.
• I ran npm run test:unit with success and extended the tests if necessary.
• I ran npm run build-all and tested the resulting file/'s from dist folder in a browser.
• I have updated the CHANGELOG.md file in the root folder.
• I have tested my code on the live network.

[coveralls]

Coverage remained the same at 84.453% when pulling ddf979f on issue/3244 into 02b695a on 1.x.

[cgewecke]

LGTM. Only thing that might be helpful is to add a regression test for this that uses the reproduction case in #3244.

// Regression test for #3244, should not throw.
it('formats the default block correctly', async function(){
    const accounts = await web3.eth.getAccounts();
    const latestBlock = await web3.eth.getBlockNumber();
    web3.eth.defaultBlock = latestBlock - 1
    await web3.eth.getBalance(accounts[0])
})

[nivida]

Only thing that might be helpful is to add a regression test for this that uses the reproduction case in #3244.

I've added an additional test case to the eth.getBalance unit test which does cover the mentioned defaultBlock case. (number -> hex)