ladybird-js support

[ChALkeR]

Mostly blocked on lifecycle: enterContext asserts on engine started,
because Promise resolution queue is broken on ladybird-js:

function f() {
  Promise.resolve().then(() => print('then'))
  print('now')
}

for (let i = 0; i < 10; i++) f()

Upstream bug: LadybirdBrowser/ladybird#7757

Broken promises is a hard blocker