devtools: Fix source contents tests and fix a race (#38359)

test_sources_list() relied on <https://servo.org/js/load-table.js> to
test scripts loaded from multiple origins, but that file was deleted a
couple of weeks ago. this patch adds a second internal web server, then
replaces that load with scripts loaded from two distinct origins:
<http://127.0.0.1:10000> and <http://127.0.0.1:10001>.

fixing that test revealed an impl bug where inline module scripts
containing `import` statements may never get their source contents
populated. this is because the logic for populating source contents for
inline scripts only applied to source actors created *before* we
finished parsing the page. we assumed that inline scripts always block
the parser, but this is not the case. this patch ensures that inline
source contents can be populated for source actors created after parse.

Testing: adds a new test,
test_source_content_with_inline_module_import_external()
Fixes: part of #36325

Signed-off-by: Delan Azabani <dazabani@igalia.com>
Co-authored-by: atbrakhi <atbrakhi@igalia.com>

components/devtools/actor.rs

@@ -84,6 +84,8 @@ pub struct ActorRegistry {
 
     /// Lookup table for SourceActor names associated with a given PipelineId.
     source_actor_names: RefCell<HashMap<PipelineId, Vec<String>>>,
+    /// Lookup table for inline source content associated with a given PipelineId.
+    inline_source_content: RefCell<HashMap<PipelineId, String>>,
 
     shareable: Option<Arc<Mutex<ActorRegistry>>>,
     next: Cell<u32>,
@@ -99,6 +101,7 @@ impl ActorRegistry {
             old_actors: RefCell::new(vec![]),
             script_actors: RefCell::new(HashMap::new()),
             source_actor_names: RefCell::new(HashMap::new()),
+            inline_source_content: RefCell::new(HashMap::new()),
             shareable: None,
             next: Cell::new(0),
             start_stamp: CrossProcessInstant::now(),
@@ -262,4 +265,20 @@ impl ActorRegistry {
 
         vec![]
     }
+
+    pub fn set_inline_source_content(&mut self, pipeline_id: PipelineId, content: String) {
+        assert!(
+            self.inline_source_content
+                .borrow_mut()
+                .insert(pipeline_id, content)
+                .is_none()
+        );
+    }
+
+    pub fn inline_source_content(&mut self, pipeline_id: PipelineId) -> Option<String> {
+        self.inline_source_content
+            .borrow()
+            .get(&pipeline_id)
+            .cloned()
+    }
 }