Feature: Subscription support

[kumavis]

This enables partial support for the experimental "web3 1.0 Ethereum JSON RPC subscriptions", covering the two most commonly used subscription types newHeads and logs.

supported subscription types:

• newHeads new block headers https://github.com/ethereum/go-ethereum/wiki/RPC-PUB-SUB#newheads
• logs evm log filter results https://github.com/ethereum/go-ethereum/wiki/RPC-PUB-SUB#logs
• newPendingTransactions get pending txs as we hear about them (somewhat functional in provider-engine, but likely not compliant)
• syncing whether the client is currently syncing blocks or not (not implemented in provider-engine either)

changes in deps

Lionshare of the changes appears in the following deps:

• metamask-inpage-provider@1.2.0
• eth-json-rpc-middleware@3.0.0
• json-rpc-engine@3.8.0
• json-rpc-middleware-stream@2.1.0
• eth-json-rpc-filters@3.0.1 <-- subs implementation

testing and QA

While subscription support is tested in the eth-json-rpc-filters module, MetaMask is lacking dapp-level integration tests. It can be QA'd like this:

• navigate to a dapp like metamask.io and open the console
• log ALL subscription hits to console

web3.currentProvider.on('data', console.log)

subscribe to newHeads

web3.currentProvider.send({ id:1, method: 'eth_subscribe', params:['newHeads']}, console.log)

subscribe to a log filter (eg DAI txs)

web3.currentProvider.send({ id:1, method: 'eth_subscribe', params:['logs', { address: '0x89d24A6b4CcB1B6fAA2625fE562bDD9a23260359'}]}, console.log)

subscribe to all logs (fire hose warning)

web3.currentProvider.send({ id:1, method: 'eth_subscribe', params:['logs', {}]}, console.log)

Relevant Issues and PRs

This PR replaces MetaMask/providers#3
Fixes #5425
Fixes #3642

[kumavis]

Addressing the "missing provider" test failures...

[metamaskbot]

Builds ready [a0700de]: mascara, chrome, firefox, edge, opera

[metamaskbot]

Builds ready [a0700de]: mascara, chrome, firefox, edge, opera

[metamaskbot]

Builds ready [9bce0ae]: mascara, chrome, firefox, edge, opera

[metamaskbot]

Builds ready [9bce0ae]: mascara, chrome, firefox, edge, opera

[metamaskbot]

Builds ready [45feb43]: mascara, chrome, firefox, edge, opera

[metamaskbot]

Builds ready [45feb43]: mascara, chrome, firefox, edge, opera

[whymarrh]

Can we add "fixes #5425" to this PR?

[HowardBraham]

@kumavis and @danfinlay, does this change the way one has to write web3 code in a Dapp?

I am using web3.js@v1.0.0-beta.36, and when I do this on Rinkeby:
let contract = new web3.eth.Contract( ...
contract.methods.transfer( ...

After this PR, the UI will show the error:
ALERT: Transaction Error. Exception thrown in contract code.

And deeper, the RPC error when calling eth_estimateGas is:
Error: [ethjs-rpc] rpc error with payload ... TypeError: blockRef.slice is not a function

My PR #5283 depends on this functionality, and I thought possibly it's just that the web3 syntax has changed.

[tmashuang]

@HowardBraham this has been fixed in MetaMask/eth-json-rpc-middleware#6

[HowardBraham]

Ahah, thank you @tmashuang!

[elie222]

So with this merged in, is Metamask now compatible with web3 1.0?