InAppBrowserEvent declaration missing

[eyecatchup]

I'm submitting a ...
[x] bug report

Current behavior:
The following code will throw a Property 'data' does not exist on type 'InAppBrowserEvent' error

this.iabRef.on('message').subscribe((event) => {
  let data = event.data;
});

The data property is available since the postMessage implementation starting in InAppBrowser version 3.1.0.

Expected behavior:
Property data needs to be defined here: https://github.com/ionic-team/ionic-native/blob/master/src/%40ionic-native/plugins/in-app-browser/index.ts#L128

Something like:

export interface InAppBrowserEvent extends Event {
    /** the event name */
    type: InAppBrowserEventType;
    /** the URL that was loaded. */
    url: string;
    /** the error code, only in the case of loaderror. */
    code: number;
    /** the error message, only in the case of loaderror. */
    message: string;
    /** the postMessage data, only in the case of message. */
    data: any;
}

Steps to reproduce:
Ionic code:

this.iabRef.on('message').subscribe((event) => {
  let data = event.data;
});
this.iabRef.executeScript({
  code: "webkit.messageHandlers.cordova_iab.postMessage(JSON.stringify({'foo': 'bar'}))"
});

Ionic info: (run ionic info from a terminal/cmd prompt and paste output below):

Ionic:

   Ionic CLI                     : 5.4.6 (/usr/local/lib/node_modules/ionic)
   Ionic Framework               : @ionic/angular 4.11.5
   @angular-devkit/build-angular : 0.801.3
   @angular-devkit/schematics    : 8.1.3
   @angular/cli                  : 8.1.3
   @ionic/angular-toolkit        : 2.1.1

Cordova:

   Cordova CLI       : 9.0.0 (cordova-lib@9.0.1)
   Cordova Platforms : android 8.1.0
   Cordova Plugins   : cordova-plugin-ionic-keyboard 2.2.0, cordova-plugin-ionic-webview 4.1.3, (and 9 other plugins)

Utility:

   cordova-res : 0.8.1
   native-run  : 0.2.9

System:

   Android SDK Tools : 26.1.1 (/Users/schmitzst/Library/Android/sdk/)
   NodeJS            : v10.17.0 (/usr/local/Cellar/node@10/10.17.0/bin/node)
   npm               : 6.11.3
   OS                : macOS Catalina
   Xcode             : Xcode 11.2.1 Build version 11B500