Add pending event listener on the VTag (#2300)

* Add pending event listener on the VTag

* Remove deprecated set_listener and rename add_listener

* Add return value comment

packages/yew/src/virtual_dom/vtag.rs

@@ -8,6 +8,7 @@ use std::borrow::Cow;
 use std::cmp::PartialEq;
 use std::hint::unreachable_unchecked;
 use std::marker::PhantomData;
+use std::mem;
 use std::ops::Deref;
 use std::rc::Rc;
 use wasm_bindgen::JsCast;
@@ -430,8 +431,22 @@ impl VTag {
             .insert(key, value.into_prop_value());
     }
 
+    /// Add event listener on the [VTag]'s  [Element].
+    /// Returns `true` if the listener has been added, `false` otherwise.
+    pub fn add_listener(&mut self, listener: Rc<dyn Listener>) -> bool {
+        if let Listeners::Pending(listeners) = &mut self.listeners {
+            let mut listeners = mem::take(listeners).into_vec();
+            listeners.push(Some(listener));
+
+            self.set_listeners(listeners.into_boxed_slice());
+            true
+        } else {
+            false
+        }
+    }
+
     /// Set event listeners on the [VTag]'s  [Element]
-    pub fn set_listener(&mut self, listeners: Box<[Option<Rc<dyn Listener>>]>) {
+    pub fn set_listeners(&mut self, listeners: Box<[Option<Rc<dyn Listener>>]>) {
         self.listeners = Listeners::Pending(listeners);
     }