Widget Window port

[ricknjacky]

In continuation of #2656
The js/widgets/widgetWindow port to ES6.

[ricknjacky]

@meganindya pls review
and tell me areas where I can improve, as this porting is a big step and my experience with the codebase is pretty nascent.
So, I'd appreciate you guiding me :)

[meganindya]

See the Reviewers section on top of the column on the right? Use that next time to request review.

I'll quickly check this

[ricknjacky]

See the Reviewers section on top of the column on the right? Use that next time to request review.

That feature is only available for members of the sugarlabs team, As you can see I don't have that access.
Correct me, if I am wrong ;-;

[meganindya]

Sorry I didn't know that. No problem with this way then. We'll come up with some conventions for the other repo once we start working on that.

[ricknjacky]

Sorry I didn't know that. No problem with this way then. We'll come up with some conventions for the other repo once we start working on that.

Are there any discrepancies in this PR tho?

[meganindya]

In all the blocks (scopes) which contain that, please check if that === this. Then replace all instances.

[ricknjacky]

In all the blocks (scopes) which contain that, please check if that === this. Then replace all instances.

Done, any other follow-ups that need some modification?

[meganindya]

You've verified that === this and there's no crash right?

[ricknjacky]

You've verified that === this and there's no crash right?

VSCode came in handy, at all instances of that VSCode referred to that as this that was declared using
let that = this ; which indeed means that that === this

[ricknjacky]

And I opened couple of widgets, they worked as expected.

[meganindya]

You've verified that === this and there's no crash right?

VSCode came in handy, at all instances of that VSCode referred to that as this that was declared using
let that = this ; which indeed means that that === this

No, I meant that you need to check it by asssestion, e.g. using console.assert() or console.log(that === this). let that = this; is what we want to remove, but then you need to check in every scope whether this is exactly equivalent to that. If you didn't use arrow functions they won't be equivalent. Just check if they are the same inside the arrow functions (they should be).