support in layout to send iframe sizes

src/components/main/constellation.rs

@@ -398,6 +398,7 @@ impl Constellation {
     }
     
     fn handle_frame_rect_msg(&mut self, pipeline_id: PipelineId, subpage_id: SubpageId, rect: Rect<f32>) {
+        debug!("Received frame rect %? from %?, %?", rect, pipeline_id, subpage_id);
         let mut already_sent = HashSet::new();
 
         // If the subframe is in the current frame tree, the compositor needs the new size
@@ -639,6 +640,7 @@ impl Constellation {
             // TODO(tkuehn): In fact, this kind of message might be provably
             // impossible to occur.
             if current_frame.contains(pipeline_id) {
+                debug!("updating compositor frame tree with %?", current_frame);
                 self.set_ids(current_frame);
                 return;
             }

src/components/main/layout/block.rs

@@ -14,6 +14,7 @@ use layout::float_context::{FloatContext, Invalid};
 
 use std::cell::Cell;
 use geom::point::Point2D;
+use geom::size::Size2D;
 use geom::rect::Rect;
 use gfx::display_list::DisplayList;
 use gfx::geometry::Au;
@@ -364,6 +365,25 @@ impl BlockFlowData {
                                                             list: &Cell<DisplayList<E>>) 
                                                             -> bool {
 
+        if self.common.node.is_iframe_element() {
+            let x = self.common.abs_position.x + do self.box.map_default(Au(0)) |box| {
+                box.with_model(|model| model.margin.left + model.border.left + model.padding.left)
+            };
+            let y = self.common.abs_position.y + do self.box.map_default(Au(0)) |box| {
+                box.with_model(|model| model.margin.top + model.border.top + model.padding.top)
+            };
+            let w = self.common.position.size.width - do self.box.map_default(Au(0)) |box| {
+                box.with_model(|model| model.noncontent_width())
+            };
+            let h = self.common.position.size.height - do self.box.map_default(Au(0)) |box| {
+                box.with_model(|model| model.noncontent_height())
+            };
+            do self.common.node.with_mut_iframe_element |iframe_element| {
+                iframe_element.size.get_mut_ref().set_rect(Rect(Point2D(x.to_f32(), y.to_f32()),
+                                                        Size2D(w.to_f32(), h.to_f32())));
+            }
+        }
+
         let abs_rect = Rect(self.common.abs_position, self.common.position.size);
         if !abs_rect.intersects(dirty) {
             return false;

src/components/main/layout/model.rs

@@ -119,6 +119,12 @@ impl BoxModel {
         left + right
     }
 
+    pub fn noncontent_height(&self) -> Au {
+        let top = self.margin.top + self.border.top + self.padding.top;
+        let bottom = self.margin.bottom + self.border.bottom + self.padding.bottom;
+        top + bottom
+    }
+
     pub fn offset(&self) -> Au {
         self.margin.left + self.border.left + self.padding.left
     }