Fix update code being generated for module variable dependencies

[j-delaney]

As discussed in #5926 (comment), I'm already working on this and should hopefully have a PR up soon.

Svelte generates update code when a class: expression is dependent on a module variable but this shouldn't happen. The docs say:

Variables defined in module scripts are not reactive — reassigning them will not trigger a rerender even though the variable itself will update.

Test Case

https://svelte.dev/repl/ca93007e0e03454fbeda66bd6e2a6b9b?version=3.32.1
If you click the button, you'll see that o is not reactive (because it's a module var). But if you look at the JS output you'll see the component's update code isn't a noop like it should be, instead it's:

p(ctx, [dirty]) {
  if (dirty & /*o*/ 0) set_data(t0, o);
  
  if (dirty & /*o*/ 0) {
    toggle_class(div, "test", o);
  }
},

Cause

I'm pretty sure that this is because is_dynamic returns true for the module var. I'm looking into whether changing that behavior will break anything though.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.