Adopt React’s element identity behavior

[brainkim]

React has a behavior where re-rendering identical elements is equal to a no-op. A justification which I read on the internet but now can no longer find is that it makes children passed in via props not update when the child component is re-rendered. So in the following Timer Component, the children would be static as the seconds are updated.

function *Timer({children}) {
  let seconds = 0;
  setInterval(() => {
    seconds++;
    this.refresh();
  }, 1000);
  for ({children} of this) {
    yield <div>{seconds} {children}</div>; 
  }
}

This is compelling, but I need to think about edge-cases.

It would also be a slightly breaking change for anyone naughty enough to mutate and re-render Crank elements because those changes would no longer be rendered.