Introduce PendingScript

This moves scripts' loading results in Document, instead of maintaining them
behind a DOMRefCell in each HTMLScriptElement.

components/script/dom/htmlscriptelement.rs

@@ -4,7 +4,6 @@
 
 use document_loader::LoadType;
 use dom::attr::Attr;
-use dom::bindings::cell::DOMRefCell;
 use dom::bindings::codegen::Bindings::AttrBinding::AttrMethods;
 use dom::bindings::codegen::Bindings::DocumentBinding::DocumentMethods;
 use dom::bindings::codegen::Bindings::HTMLScriptElementBinding;
@@ -61,9 +60,6 @@ pub struct HTMLScriptElement {
 
     /// Document of the parser that created this element
     parser_document: JS<Document>,
-
-    /// The source this script was loaded from
-    load: DOMRefCell<Option<Result<ClassicScript, NetworkError>>>,
 }
 
 impl HTMLScriptElement {
@@ -77,7 +73,6 @@ impl HTMLScriptElement {
             non_blocking: Cell::new(creator != ElementCreator::ParserCreated),
             ready_to_be_parser_executed: Cell::new(false),
             parser_document: JS::from_ref(document),
-            load: DOMRefCell::new(None),
         }
     }
 
@@ -137,10 +132,14 @@ impl ClassicScript {
     }
 }
 
+pub type ScriptResult = Result<ClassicScript, NetworkError>;
+
 /// The context required for asynchronously loading an external script source.
 struct ScriptContext {
     /// The element that initiated the request.
     elem: Trusted<HTMLScriptElement>,
+    /// The kind of external script.
+    kind: ExternalScriptKind,
     /// The (fallback) character encoding argument to the "fetch a classic
     /// script" algorithm.
     character_encoding: EncodingRef,
@@ -207,10 +206,16 @@ impl FetchResponseListener for ScriptContext {
         // https://html.spec.whatwg.org/multipage/#prepare-a-script
         // Step 18.6 (When the chosen algorithm asynchronously completes).
         let elem = self.elem.root();
-        *elem.load.borrow_mut() = Some(load);
         elem.ready_to_be_parser_executed.set(true);
-
         let document = document_from_node(&*elem);
+
+        match self.kind {
+            ExternalScriptKind::Asap => document.asap_script_loaded(&elem, load),
+            ExternalScriptKind::AsapInOrder => document.asap_in_order_script_loaded(&elem, load),
+            ExternalScriptKind::Deferred => document.deferred_script_loaded(&elem, load),
+            ExternalScriptKind::ParsingBlocking => document.pending_parsing_blocking_script_loaded(&elem, load),
+        }
+
         document.finish_load(LoadType::Script(self.url.clone()));
     }
 }
@@ -219,6 +224,7 @@ impl PreInvoke for ScriptContext {}
 
 /// https://html.spec.whatwg.org/multipage/#fetch-a-classic-script
 fn fetch_a_classic_script(script: &HTMLScriptElement,
+                          kind: ExternalScriptKind,
                           url: ServoUrl,
                           cors_setting: Option<CorsSettings>,
                           integrity_metadata: String,
@@ -254,6 +260,7 @@ fn fetch_a_classic_script(script: &HTMLScriptElement,
 
     let context = Arc::new(Mutex::new(ScriptContext {
         elem: Trusted::new(script),
+        kind: kind,
         character_encoding: character_encoding,
         data: vec!(),
         metadata: None,
@@ -422,19 +429,19 @@ impl HTMLScriptElement {
             };
 
             // Step 20.6.
-            fetch_a_classic_script(self, url, cors_setting, integrity_metadata.to_owned(), encoding);
+            fetch_a_classic_script(self, kind, url, cors_setting, integrity_metadata.to_owned(), encoding);
 
             // Step 22.
             match kind {
                 ExternalScriptKind::Deferred => doc.add_deferred_script(self),
-                ExternalScriptKind::ParsingBlocking => doc.set_pending_parsing_blocking_script(self),
+                ExternalScriptKind::ParsingBlocking => doc.set_pending_parsing_blocking_script(self, None),
                 ExternalScriptKind::AsapInOrder => doc.push_asap_in_order_script(self),
                 ExternalScriptKind::Asap => doc.add_asap_script(self),
             }
         } else {
             // Step 21.
             assert!(!text.is_empty());
-            *self.load.borrow_mut() = Some(Ok(ClassicScript::internal(text, base_url)));
+            let result = Ok(ClassicScript::internal(text, base_url));
             self.ready_to_be_parser_executed.set(true);
 
             // Step 22.
@@ -442,10 +449,10 @@ impl HTMLScriptElement {
                doc.get_current_parser().map_or(false, |parser| parser.script_nesting_level() <= 1) &&
                doc.get_script_blocking_stylesheets_count() > 0 {
                 // Step 22.e: classic, has no src, was parser-inserted, is blocked on stylesheet.
-                doc.set_pending_parsing_blocking_script(self);
+                doc.set_pending_parsing_blocking_script(self, Some(result));
             } else {
                 // Step 22.f: otherwise.
-                self.execute();
+                self.execute(result);
             }
         }
     }
@@ -455,7 +462,7 @@ impl HTMLScriptElement {
     }
 
     /// https://html.spec.whatwg.org/multipage/#execute-the-script-block
-    pub fn execute(&self) {
+    pub fn execute(&self, result: Result<ClassicScript, NetworkError>) {
         assert!(self.ready_to_be_parser_executed.get());
 
         // Step 1.
@@ -464,8 +471,7 @@ impl HTMLScriptElement {
             return;
         }
 
-        let load = self.load.borrow_mut().take().unwrap();
-        let script = match load {
+        let script = match result {
             // Step 2.
             Err(e) => {
                 warn!("error loading script {:?}", e);