Patch the closure type for AbortController.abort() to gen correct code

[realityforge]

Prior to this patch the AbortController generated a class

@JsType(isNative = true, namespace = JsPackage.GLOBAL)
public class AbortController {
  @JsFunction
  public interface AbortFn {
    Object onInvoke();
  }

  public AbortController.AbortFn abort;
  public AbortSignal signal;
}

However when this was used in a GWT 2.8.2 it would produce incorrect code. For example _abortController.abort.onInvoke() would be compiled to this._abortController.abort.call(null) which would result in an error from the browser.

The patched closure extern will generate working code that looks like:

@JsType( isNative = true, namespace = JsPackage.GLOBAL )
public class AbortController
{
  public AbortSignal signal;

  public native void abort();
}

[gkdn]

Pls send a PR to extern file in Closure instead.

[realityforge]

Closed in favour of https://github.com/google/closure-compiler/pull/3209