Auto merge of #24576 - jaymodi98:iframe-srcdoc, r=jdm

Implement srcdoc support for iframes

<!-- Please describe your changes on the following line: -->
This PR contains changes related to adding srcdoc attribute parsing support for iframes in Servo. The following changes have been made:

- uncomment the [srcdoc](f63b404e0c/components/script/dom/webidls/HTMLIFrameElement.webidl (L10-L11)) WebIDL attribute, and implement the attribute getter.
- add a field to [LoadData](e6b271d329/components/script_traits/lib.rs (L137-L164)) for storing the srcdoc contents when loading a srcdoc iframe.
- (partially) implemented a new `page_load_about_srcdoc` method to `script_thread.rs` which loads the special `about:srcdoc` URL [per the specification](https://html.spec.whatwg.org/multipage/iframe-embed-object.html#process-the-iframe-attributes) and takes the srcdoc contents as an argument
- call this new method from [handle_new_layout](e6b271d329/components/script/script_thread.rs (L2409-L2412)) when it's detected that a srcdoc iframe is being loaded
- (partially) in [attribute_mutated](e6b271d329/components/script/dom/htmliframeelement.rs (L560)), ensure that changing the `srcdoc` attribute of an iframe element [follows the specification](https://html.spec.whatwg.org/multipage/iframe-embed-object.html#the-iframe-element:the-iframe-element-9).

---
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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes are a part of fix #4767  (GitHub issue number if applicable)

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components/script/dom/htmliframeelement.rs

@@ -130,10 +130,12 @@ impl HTMLIFrameElement {
 
         let document = document_from_node(self);
 
-        let mut load_blocker = self.load_blocker.borrow_mut();
-        // Any oustanding load is finished from the point of view of the blocked
-        // document; the new navigation will continue blocking it.
-        LoadBlocker::terminate(&mut load_blocker);
+        {
+            let mut load_blocker = self.load_blocker.borrow_mut();
+            // Any oustanding load is finished from the point of view of the blocked
+            // document; the new navigation will continue blocking it.
+            LoadBlocker::terminate(&mut load_blocker);
+        }
 
         if load_data.url.scheme() == "javascript" {
             let window_proxy = self.GetContentWindow();
@@ -150,6 +152,7 @@ impl HTMLIFrameElement {
         match load_data.js_eval_result {
             Some(JsEvalResult::NoContent) => (),
             _ => {
+                let mut load_blocker = self.load_blocker.borrow_mut();
                 *load_blocker = Some(LoadBlocker::new(
                     &*document,
                     LoadType::Subframe(load_data.url.clone()),
@@ -229,7 +232,30 @@ impl HTMLIFrameElement {
 
     /// <https://html.spec.whatwg.org/multipage/#process-the-iframe-attributes>
     fn process_the_iframe_attributes(&self, mode: ProcessingMode) {
-        // TODO: srcdoc
+        if self
+            .upcast::<Element>()
+            .has_attribute(&local_name!("srcdoc"))
+        {
+            let url = ServoUrl::parse("about:srcdoc").unwrap();
+            let document = document_from_node(self);
+            let window = window_from_node(self);
+            let pipeline_id = Some(window.upcast::<GlobalScope>().pipeline_id());
+            let mut load_data = LoadData::new(
+                LoadOrigin::Script(document.origin().immutable().clone()),
+                url,
+                pipeline_id,
+                Some(Referrer::ReferrerUrl(document.url())),
+                document.get_referrer_policy(),
+            );
+            let element = self.upcast::<Element>();
+            load_data.srcdoc = String::from(element.get_string_attribute(&local_name!("srcdoc")));
+            self.navigate_or_reload_child_browsing_context(
+                load_data,
+                NavigationType::InitialAboutBlank,
+                HistoryEntryReplacement::Disabled,
+            );
+            return;
+        }
 
         let window = window_from_node(self);
 
@@ -480,6 +506,12 @@ impl HTMLIFrameElementMethods for HTMLIFrameElement {
     // https://html.spec.whatwg.org/multipage/#dom-iframe-src
     make_url_setter!(SetSrc, "src");
 
+    // https://html.spec.whatwg.org/multipage/#dom-iframe-srcdoc
+    make_getter!(Srcdoc, "srcdoc");
+
+    // https://html.spec.whatwg.org/multipage/#dom-iframe-srcdoc
+    make_setter!(SetSrcdoc, "srcdoc");
+
     // https://html.spec.whatwg.org/multipage/#dom-iframe-sandbox
     fn Sandbox(&self) -> DomRoot<DOMTokenList> {
         self.sandbox
@@ -580,13 +612,29 @@ impl VirtualMethods for HTMLIFrameElement {
                         modes
                     }));
             },
+            &local_name!("srcdoc") => {
+                // https://html.spec.whatwg.org/multipage/#the-iframe-element:the-iframe-element-9
+                // "Whenever an iframe element with a non-null nested browsing context has its
+                // srcdoc attribute set, changed, or removed, the user agent must process the
+                // iframe attributes."
+                // but we can't check that directly, since the child browsing context
+                // may be in a different script thread. Instead, we check to see if the parent
+                // is in a document tree and has a browsing context, which is what causes
+                // the child browsing context to be created.
+
+                // trigger the processing of iframe attributes whenever "srcdoc" attribute is set, changed or removed
+                if self.upcast::<Node>().is_connected_with_browsing_context() {
+                    debug!("iframe srcdoc modified while in browsing context.");
+                    self.process_the_iframe_attributes(ProcessingMode::NotFirstTime);
+                }
+            },
             &local_name!("src") => {
                 // https://html.spec.whatwg.org/multipage/#the-iframe-element
                 // "Similarly, whenever an iframe element with a non-null nested browsing context
                 // but with no srcdoc attribute specified has its src attribute set, changed, or removed,
                 // the user agent must process the iframe attributes,"
                 // but we can't check that directly, since the child browsing context
-                // may be in a different script thread. Instread, we check to see if the parent
+                // may be in a different script thread. Instead, we check to see if the parent
                 // is in a document tree and has a browsing context, which is what causes
                 // the child browsing context to be created.
                 if self.upcast::<Node>().is_connected_with_browsing_context() {

components/script/dom/webidls/HTMLIFrameElement.webidl

@@ -9,8 +9,8 @@ interface HTMLIFrameElement : HTMLElement {
 
   [CEReactions]
            attribute USVString src;
-  // [CEReactions]
-  //         attribute DOMString srcdoc;
+  [CEReactions]
+           attribute DOMString srcdoc;
 
   [CEReactions]
   attribute DOMString name;

components/script/script_thread.rs

@@ -2430,6 +2430,8 @@ impl ScriptThread {
         );
         if load_data.url.as_str() == "about:blank" {
             self.start_page_load_about_blank(new_load, load_data.js_eval_result);
+        } else if load_data.url.as_str() == "about:srcdoc" {
+            self.page_load_about_srcdoc(new_load, load_data.srcdoc);
         } else {
             self.pre_page_load(new_load, load_data);
         }
@@ -3177,7 +3179,8 @@ impl ScriptThread {
             self.timer_event_chan.clone(),
         );
 
-        let origin = if final_url.as_str() == "about:blank" {
+        let origin = if final_url.as_str() == "about:blank" || final_url.as_str() == "about:srcdoc"
+        {
             incomplete.origin.clone()
         } else {
             MutableOrigin::new(final_url.origin())
@@ -3838,6 +3841,25 @@ impl ScriptThread {
         context.process_response_eof(Ok(ResourceFetchTiming::new(ResourceTimingType::None)));
     }
 
+    /// Synchronously parse a srcdoc document from a giving HTML string.
+    fn page_load_about_srcdoc(&self, incomplete: InProgressLoad, src_doc: String) {
+        let id = incomplete.pipeline_id;
+
+        self.incomplete_loads.borrow_mut().push(incomplete);
+
+        let url = ServoUrl::parse("about:srcdoc").unwrap();
+        let mut context = ParserContext::new(id, url.clone());
+
+        let mut meta = Metadata::default(url);
+        meta.set_content_type(Some(&mime::TEXT_HTML));
+
+        let chunk = src_doc.into_bytes();
+
+        context.process_response(Ok(FetchMetadata::Unfiltered(meta)));
+        context.process_response_chunk(chunk);
+        context.process_response_eof(Ok(ResourceFetchTiming::new(ResourceTimingType::None)));
+    }
+
     fn handle_css_error_reporting(
         &self,
         pipeline_id: PipelineId,

components/script_traits/lib.rs

@@ -163,6 +163,9 @@ pub struct LoadData {
     pub referrer: Option<Referrer>,
     /// The referrer policy.
     pub referrer_policy: Option<ReferrerPolicy>,
+
+    /// The source to use instead of a network response for a srcdoc document.
+    pub srcdoc: String,
 }
 
 /// The result of evaluating a javascript scheme url.
@@ -194,6 +197,7 @@ impl LoadData {
             js_eval_result: None,
             referrer: referrer,
             referrer_policy: referrer_policy,
+            srcdoc: "".to_string(),
         }
     }
 }