fix evaluateJavascript

Author: p-mazhnik

flutter_inappwebview_web/lib/web/in_app_web_view_web_element.dart

@@ -326,7 +326,7 @@ class InAppWebViewWebElement implements Disposable {
   }
 
   Future<dynamic> evaluateJavascript({required String source}) async {
-    jsWebView?.evaluateJavascript(source.toJS);
+    return jsWebView?.evaluateJavascript(source.toJS)?.toDart;
   }
 
   Future<void> stopLoading() async {

flutter_inappwebview_web/lib/web/js_bridge.dart

@@ -17,7 +17,7 @@ extension type JSWebView._(JSObject _) implements JSObject {
   external void goBack();
   external void goForward();
   external void goBackOrForward(JSNumber steps);
-  external void evaluateJavascript(JSString source);
+  external JSString? evaluateJavascript(JSString source);
   external void stopLoading();
   external JSString? getUrl();
   external JSString? getTitle();