refactor(nav-controller): add data property to the leaving opts so it's accessible to transition w

add data property to the leaving opts so it's accessible to transition when exiting

src/components/nav/nav-controller.ts

@@ -505,7 +505,8 @@ export class NavController extends Ion {
     enteringView.setLeavingOpts({
       keyboardClose: false,
       direction: 'back',
-      animation: enteringView.getTransitionName('back')
+      animation: enteringView.getTransitionName('back'),
+      ev: opts.ev
     });
 
     // start the transition