This is a reland of commit 54522db98f
Original change's description:
> [dart2wasm] Fix nullable JS type and int parameters in JSFunction
>
> When a callback is toJS'd with an int parameter, we should attempt
> a conversion to int if possible, similar to return values on
> external functions. Similarly, parameters where the expected type is
> a JS type should check to make the value isn't nullish before boxing,
> as JS null and undefined are converted to Dart null.
>
> Tests are added for conversion semantics of JSFunctions.
>
> Change-Id: I95566c2954d915b8cf31cdc55fed359c695404f2
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/323445
> Reviewed-by: Aske Simon Christensen <askesc@google.com>
Change-Id: I36ec7702b1e08fc9e4d6290952ae548b0e074ee3
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/325971
Reviewed-by: Sigmund Cherem <sigmund@google.com>
Commit-Queue: Srujan Gaddam <srujzs@google.com>
Srujan Gaddam
39e8c57963