Workletizable Context Objects

[tjzel]

This pull request introduces the concept of Context Objects on the Worklet Runtime.

What?

Context Object is a shareable object that doesn't lose its this binding when it goes to the Worklet Runtime. To define an object as a Context Object, the user has to define property __workletObject on it. (Should it be __contextObject?)

Why?

Currently it's not possible to refer to an object's methods from its other methods.

const obj = {
  foo() {
    console.log("foo");
  }
  bar() {
    this.foo();
  }
}

runOnUI(() => {
  obj.bar(); // Crash, the binding is lost on serialization.
})();

How?

Context Objects are handled as another type of shareable entity on the React Runtime.

1. The plugin adds a special property __workletObjectFactory to Context Objects. It's a function that creates an identical object.
2. We serialize the factory instead of the object itself.
3. We recreate the object on the Worklet Runtime via ShareableHandle mechanism.

Test plan

• Add unit tests
• Add a runtime test suite