Write reflow results, even with no root node.

Fixes #8240

1 files changed, 28 insertions, 4 deletions

diff --git a/components/layout/layout_task.rs b/components/layout/layout_task.rs
index d650a927ad3..603a08491d0 100644
--- a/components/layout/layout_task.rs
+++ b/components/layout/layout_task.rs
@@ -1082,21 +1082,45 @@ impl LayoutTask {
 
         let document = unsafe { LayoutNode::new(&data.document) };
         let document = document.as_document().unwrap();
+
+        debug!("layout: received layout request for: {}", self.url.serialize());
+
+        let mut rw_data = possibly_locked_rw_data.lock();
+
         let node: LayoutNode = match document.root_node() {
-            None => return,
+            None => {
+                // Since we cannot compute anything, give spec-required placeholders.
+                debug!("layout: No root node: bailing");
+                match data.query_type {
+                    ReflowQueryType::ContentBoxQuery(_) => {
+                        rw_data.content_box_response = Rect::zero();
+                    },
+                    ReflowQueryType::ContentBoxesQuery(_) => {
+                        rw_data.content_boxes_response = Vec::new();
+                    },
+                    ReflowQueryType::NodeGeometryQuery(_) => {
+                        rw_data.client_rect_response = Rect::zero();
+                    },
+                    ReflowQueryType::ResolvedStyleQuery(_, _, _) => {
+                        rw_data.resolved_style_response = None;
+                    },
+                    ReflowQueryType::OffsetParentQuery(_) => {
+                        rw_data.offset_parent_response = OffsetParentResponse::empty();
+                    },
+                    ReflowQueryType::NoQuery => {}
+                }
+                return;
+            },
             Some(x) => x,
         };
 
-        debug!("layout: received layout request for: {}", self.url.serialize());
         if log_enabled!(log::LogLevel::Debug) {
             node.dump();
         }
 
-        let mut rw_data = possibly_locked_rw_data.lock();
         let stylesheets: Vec<&Stylesheet> = data.document_stylesheets.iter().map(|entry| &**entry)
                                                                             .collect();
         let stylesheets_changed = data.stylesheets_changed;
-
         let initial_viewport = data.window_size.initial_viewport;
         let old_viewport_size = self.viewport_size;
         let current_screen_size = Size2D::new(Au::from_f32_px(initial_viewport.width.get()),