"javascript:" urls: evaluate in iframe src attribute

- generalize the eval_js_url function so it can be called from
  multiple places.
- call it in htmliframeelement.
- if the js eval results in a non-string result, then it won't
  navigate to a new page, so don't block on the new page loading.

components/constellation/constellation.rs

@@ -1056,7 +1056,7 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
                 self.handle_load_url_msg(source_top_ctx_id, source_pipeline_id, load_data, replace);
             }
             FromScriptMsg::AbortLoadUrl => {
-                debug!("constellation got URL load message from script");
+                debug!("constellation got abort URL load message from script");
                 self.handle_abort_load_url_msg(source_pipeline_id);
             }
             // A page loaded has completed all parsing, script, and reflow messages have been sent.

components/script/dom/htmliframeelement.rs

@@ -44,7 +44,7 @@ use msg::constellation_msg::{FrameType, BrowsingContextId, PipelineId, TopLevelB
 use net_traits::response::HttpsState;
 use script_layout_interface::message::ReflowQueryType;
 use script_thread::{ScriptThread, Runnable};
-use script_traits::{IFrameLoadInfo, IFrameLoadInfoWithData, LoadData, UpdatePipelineIdReason};
+use script_traits::{IFrameLoadInfo, IFrameLoadInfoWithData, JsEvalResult, LoadData, UpdatePipelineIdReason};
 use script_traits::{MozBrowserEvent, NewLayoutInfo, ScriptMsg};
 use script_traits::IFrameSandboxState::{IFrameSandboxed, IFrameUnsandboxed};
 use servo_atoms::Atom;
@@ -114,7 +114,7 @@ impl HTMLIFrameElement {
     }
 
     pub fn navigate_or_reload_child_browsing_context(&self,
-                                                     load_data: Option<LoadData>,
+                                                     mut load_data: Option<LoadData>,
                                                      nav_type: NavigationType,
                                                      replace: bool) {
         let sandboxed = if self.is_sandboxed() {
@@ -140,11 +140,26 @@ impl HTMLIFrameElement {
         // document; the new navigation will continue blocking it.
         LoadBlocker::terminate(&mut load_blocker);
 
+        if let Some(ref mut load_data) = load_data {
+            let is_javascript = load_data.url.scheme() == "javascript";
+            if is_javascript {
+                let window_proxy = self.GetContentWindow();
+                if let Some(window_proxy) = window_proxy {
+                    ScriptThread::eval_js_url(&window_proxy.global(), load_data);
+                }
+            }
+        }
+
         //TODO(#9592): Deal with the case where an iframe is being reloaded so url is None.
         //      The iframe should always have access to the nested context's active
         //      document URL through the browsing context.
         if let Some(ref load_data) = load_data {
-            *load_blocker = Some(LoadBlocker::new(&*document, LoadType::Subframe(load_data.url.clone())));
+            match load_data.js_eval_result {
+                Some(JsEvalResult::NoContent) => (),
+                _ => {
+                    *load_blocker = Some(LoadBlocker::new(&*document, LoadType::Subframe(load_data.url.clone())));
+                }
+            };
         }
 
         let window = window_from_node(self);

components/script/script_thread.rs

@@ -2312,7 +2312,10 @@ impl ScriptThread {
                               replace: bool) {
         let is_javascript = load_data.url.scheme() == "javascript";
         if is_javascript {
-            self.eval_js_url(parent_pipeline_id, &mut load_data);
+            let window = self.documents.borrow().find_window(parent_pipeline_id);
+            if let Some(window) = window {
+                ScriptThread::eval_js_url(window.upcast::<GlobalScope>(), &mut load_data);
+            }
         }
 
         match browsing_context_id {
@@ -2330,7 +2333,7 @@ impl ScriptThread {
         }
     }
 
-    fn eval_js_url(&self, pipeline_id: PipelineId, load_data: &mut LoadData) {
+    pub fn eval_js_url(global_scope: &GlobalScope, load_data: &mut LoadData) {
         {
             // Turn javascript: URL into JS code to eval, according to the steps in
             // https://html.spec.whatwg.org/multipage/#javascript-protocol
@@ -2345,30 +2348,25 @@ impl ScriptThread {
             let script_source = percent_decode(encoded.as_bytes()).decode_utf8_lossy();
 
             // Script source is ready to be evaluated (11.)
-            let window = self.documents.borrow().find_window(pipeline_id);
-
-            if let Some(window) = window {
-                let _ac = JSAutoCompartment::new(self.get_cx(), window.reflector().get_jsobject().get());
-                rooted!(in(self.get_cx()) let mut jsval = UndefinedValue());
-                window.upcast::<GlobalScope>().evaluate_js_on_global_with_result(
-                    &script_source, jsval.handle_mut());
-
-                load_data.js_eval_result = if jsval.get().is_string() {
-                    unsafe {
-                        let strval = DOMString::from_jsval(self.get_cx(),
-                                                           jsval.handle(),
-                                                           StringificationBehavior::Empty);
-                        match strval {
-                            Ok(ConversionResult::Success(s)) => {
-                                Some(JsEvalResult::Ok(String::from(s).as_bytes().to_vec()))
-                            },
-                            _ => None,
-                        }
+            let _ac = JSAutoCompartment::new(global_scope.get_cx(), global_scope.reflector().get_jsobject().get());
+            rooted!(in(global_scope.get_cx()) let mut jsval = UndefinedValue());
+            global_scope.evaluate_js_on_global_with_result(&script_source, jsval.handle_mut());
+
+            load_data.js_eval_result = if jsval.get().is_string() {
+                unsafe {
+                    let strval = DOMString::from_jsval(global_scope.get_cx(),
+                                                       jsval.handle(),
+                                                       StringificationBehavior::Empty);
+                    match strval {
+                        Ok(ConversionResult::Success(s)) => {
+                            Some(JsEvalResult::Ok(String::from(s).as_bytes().to_vec()))
+                        },
+                        _ => None,
                     }
-                } else {
-                    Some(JsEvalResult::NoContent)
-                };
-            }
+                }
+            } else {
+                Some(JsEvalResult::NoContent)
+            };
         };
 
         load_data.url = ServoUrl::parse("about:blank").unwrap();