[playground] sourcemaps should be 1:many

[Rich-Harris]

Most of the time, sourcemaps are 1:1. Sometimes, they're not. In a case like this...

<script>
  let user = $state({ name: 'alice' });
</script>

<input bind:value={user.name}>

...this code is generated in dev mode...

$.validate_binding("bind:value={user.name}", () => user, () => "name", 5, 7);
$.bind_value(input, () => user.name, ($$value) => $.assign(user, "name", $$value, "App.svelte:5:19"));

...and hovering over the user in the editor will only highlight the first of two possible mappings in the output:

Ideally, both would be highlighted