feat(example:todomvc): add editing support

- implement "onfocusout" handler
- set autofocus
- handle enter, escape and tab on a todo item
- make the `<pre>` element between todo list items of margin 0 to be unnoticable

packages/web/src/cache.rs

@@ -203,6 +203,7 @@ pub static BUILTIN_INTERNED_STRINGS: &[&'static str] = &[
     "onended",
     "onerror",
     "onfocus",
+    "onfocusout",
     "onhashchange",
     "oninput",
     "oninvalid",