fix: remove ambiguous "this" in favor of passed event and currentTarget

[jsr6720]

"this" can be ambiguous in JS. So let's use the event that's already passed to the function.

[dylans]

Not sure I agree with this change, as the on API makes it clear that this always refers to the event target within the callback function.

[jsr6720]

@dylans agreed. Turns out we have some internal code that is hijacking the event. Though I was curious why the event is not used? Is this the same pattern for TypeScript?

[dylans]

We generally only include the event object as a parameter when we use it... saves an object in memory basically. It's still there as the first argument though, so you could read it from arguments[0] for example.

[jsr6720]

Thanks for the feedback. We're going to fix the conflict internally.