fix(core): Return the window object as default instead of the boolean…

… from the typeof comparison (#3160)

* Fixes #2972

#2972

* If window does not exist.

But is there a case where window does not exist? If ionic-native always runs in browsers enviroment (like Cordova / WebView) we could remove the `typeof` checks.

src/@ionic-native/core/decorators/common.ts

@@ -149,7 +149,7 @@ function wrapObservable(pluginObj: any, methodName: string, args: any[], opts: a
  * @returns {Observable}
  */
 function wrapEventObservable(event: string, element: any): Observable<any> {
-  element = (typeof window !== 'undefined' && element) ? get(window, element) : element || typeof window !== 'undefined' || {};
+  element = (typeof window !== 'undefined' && element) ? get(window, element) : element || (typeof window !== 'undefined' ? window : {});
   return fromEvent(element, event);
 }