Bug 1519053 - Set window handle for 'Switch To Window' also as 'handle'. r=whimboo

Differential Revision: https://phabricator.services.mozilla.com/D23169

--HG--
extra : moz-landing-system : lando

testing/geckodriver/src/marionette.rs

@@ -1476,6 +1476,10 @@ impl ToMarionette for SwitchToWindowParameters {
             "name".to_string(),
             serde_json::to_value(self.handle.clone())?,
         );
+        data.insert(
+            "handle".to_string(),
+            serde_json::to_value(self.handle.clone())?,
+        );
         Ok(data)
     }
 }