Execution order with async functions/then isn' the same with the origin code

Bug Report

Current Behavior

Compiled code’s execution order with async functions isn’ the same with the origin code. More detail below.

Origin:

Compiled:

Input Code

• REPL or Repo link if applicable

async function async1() {
  const p = async2()
  p.then(() => console.log('async2 1st then'))
  await p
  console.log('async2 after await')
}

async function async2() {
  console.log('async2')
}

async1()
new Promise(resolve => {
  console.log('2rd promise handler')
  resolve()
}).then(() => {
  console.log('2rd promise 1st then')
})

Expected behavior/code

The above code should behave exactly the same, as in Chrome 71+:

Environment

• Babel version(s): 6.26.0
• Node/npm version: Node 11
• Chrome: 71

Additional context/Screenshots

The behavior was inconsistent in older versions of node and chrome, but now they seem to be aligned.

[jridgewell]

Because the spec removed the extra tick when awaiting native promises, Babel’s behavior is the correct behavior. Fixed for free!

[zloirock]

I think that makes sense to add a test for this behavior to compat-table.