currentScript property not exists in Document interface

[emilgpa]

The currentScript not exists in Document interface.

[mhegazy]

A PR would be appreciated. here is some information about submitting a lib.d.ts PR: https://github.com/Microsoft/TypeScript/blob/master/CONTRIBUTING.md#contributing-libdts-fixes

[emilgpa]

Ok. Nice. I will do it now!

[zhengbli]

This is fixed in microsoft/TypeScript-DOM-lib-generator#17

[mhegazy]

@zhengbli should we close this? Or you want to do a port first?

[zhengbli]

@mhegazy I think these issues should be closed only when the changes are checked in the TypeScript repo. It might be easier to track if we can add a new label to these ones, something like "Fixed in TSJS" so we can close them in batch when syncing with that repo.