script: Expose NodeTraits::owner_global / Window::as_global_scope (#34843)

Expose two new helpers and start using them as much as possible.

- `NodeTraits::owner_global`: which gets the `GlobalScope` that currenty
 owns a `Node`. This may be different than `.global()` in the case that
 the `Node` was adopted by a different `Document`.
- `Window::as_global_scope`: A helper to avoid having to cast so much
  when treating a `Window` like a `GlobalScope`.

Signed-off-by: Martin Robinson <mrobinson@igalia.com>

components/script/script_module.rs

@@ -942,7 +942,7 @@ pub(crate) enum ModuleOwner {
 }
 
 impl ModuleOwner {
-    pub fn global(&self) -> DomRoot<GlobalScope> {
+    pub(crate) fn global(&self) -> DomRoot<GlobalScope> {
         match &self {
             ModuleOwner::Worker(worker) => (*worker.root().clone()).global(),
             ModuleOwner::Window(script) => (*script.root()).global(),