Add dyn keyword where necessary

src/platform_impl/web/web_sys/canvas.rs

@@ -233,7 +233,7 @@ impl Canvas {
         }));
     }
 
-    fn add_event<E, F>(&self, event_name: &str, mut handler: F) -> Closure<FnMut(E)>
+    fn add_event<E, F>(&self, event_name: &str, mut handler: F) -> Closure<dyn FnMut(E)>
     where
         E: 'static + AsRef<web_sys::Event> + wasm_bindgen::convert::FromWasmAbi,
         F: 'static + FnMut(E),

src/platform_impl/web/web_sys/timeout.rs

@@ -5,7 +5,7 @@ use wasm_bindgen::JsCast;
 #[derive(Debug)]
 pub struct Timeout {
     handle: i32,
-    _closure: Closure<FnMut()>,
+    _closure: Closure<dyn FnMut()>,
 }
 
 impl Timeout {