feat(reactivity): remove redundant code

[Ali-ovo]

When I was studying the source code from vue3 reactivity
I found that on computed this section there was bloated code
So I thought we could remove it, and the test passed successfully

[skirtles-code]

This PR is currently marked as a feat. I wonder whether refactor might be more appropriate?

The line public dep?: Dep = undefined features in several of the ref implementations. e.g. RefImpl and CustomRefImpl. If we're going to remove it from one then maybe it should be removed from all of them?

The property itself comes from the RefBase type, which marks it as optional. That property is then used in trackRefValue and triggerRefValue. As the property is optional, nothing complains if the initial value isn't explicitly set to undefined, but nevertheless the property will be added once the ref is used elsewhere.

I'm unsure what the reasoning was behind explicitly declaring these properties with undefined values. Perhaps it was just for greater explicitness, or maybe it was to ensure that the 'shape' of the objects won't change at runtime post-creation (for better performance).

[Ali-ovo]

This PR is currently marked as a feat. I wonder whether refactor might be more appropriate?

The line public dep?: Dep = undefined features in several of the ref implementations. e.g. RefImpl and CustomRefImpl. If we're going to remove it from one then maybe it should be removed from all of them?

The property itself comes from the RefBase type, which marks it as optional. That property is then used in trackRefValue and triggerRefValue. As the property is optional, nothing complains if the initial value isn't explicitly set to undefined, but nevertheless the property will be added once the ref is used elsewhere.

I'm unsure what the reasoning was behind explicitly declaring these properties with undefined values. Perhaps it was just for greater explicitness, or maybe it was to ensure that the 'shape' of the objects won't change at runtime post-creation (for better performance).

Oh, you're right. I made a mistake