dillon1000/react

Reduce scheduler serialization overhead (#14249)

In the process of switching to MessageChannel, it seems the postMessage call was modified to pass `"*"` (originally the target origin value from `window.postMessage`). This actually ends up triggering serialization, whereas passing `undefined` bypasses.

To save some investigation, passing a Number like `0` still incurs serialization overhead - `undefined` has special behavior.