Feat: support share customized JS properties in event object.

[andycall]

Support sharing JS objects properties in multiple event callbacks.

var p = document.createElement('p');

p.addEventListener('click', (e) => {  ee = e;
  e.dataName3 = {age: 10};
}, true);

p.addEventListener('click', (e) => {
  e.dataName3.age = 20;
});

document.body.addEventListener('click', (e) => {
  console.log('aaa', e.dataName3);
});

document.body.appendChild(p);