layout: Fix percentages in relatively positioned elements

4 files changed, 12 insertions, 11 deletions

diff --git a/src/components/main/layout/block.rs b/src/components/main/layout/block.rs
index 5a731fbd748..0ba75a4a53b 100644
--- a/src/components/main/layout/block.rs
+++ b/src/components/main/layout/block.rs
@@ -1171,7 +1171,7 @@ impl BlockFlow {
         let mut info = *info;
         let mut rel_offset = Point2D(Au(0), Au(0));
         for fragment in self.box_.iter() {
-            rel_offset = fragment.relative_position(&info.containing_block_size);
+            rel_offset = fragment.relative_position(&info.relative_containing_block_size);
 
             // Add the box that starts the block context.
             fragment.build_display_list(stacking_context,
@@ -1184,11 +1184,12 @@ impl BlockFlow {
             // For relatively-positioned descendants, the containing block formed by a block is
             // just the content box. The containing block for absolutely-positioned descendants,
             // on the other hand, only established if we are positioned.
-            let container_block_size = fragment.content_box_size();
+            info.relative_containing_block_size = fragment.content_box_size();
             if self.is_positioned() {
-                info.absolute_containing_block_position = self.base.abs_position +
+                info.absolute_containing_block_position =
+                    self.base.abs_position +
                     self.generated_cb_position() +
-                    fragment.relative_position(&container_block_size)
+                    fragment.relative_position(&info.relative_containing_block_size)
             }
         }
 
diff --git a/src/components/main/layout/display_list_builder.rs b/src/components/main/layout/display_list_builder.rs
index 4779c913fc4..3bec56473c3 100644
--- a/src/components/main/layout/display_list_builder.rs
+++ b/src/components/main/layout/display_list_builder.rs
@@ -26,9 +26,9 @@ pub struct DisplayListBuilder<'a> {
 
 /// Information needed at each step of the display list building traversal.
 pub struct DisplayListBuildingInfo {
-    /// The size of the containing block.
-    containing_block_size: Size2D<Au>,
-    /// The absolute position of the absolute containing block.
+    /// The size of the containing block for relatively-positioned descendants.
+    relative_containing_block_size: Size2D<Au>,
+    /// The position and size of the absolute containing block.
     absolute_containing_block_position: Point2D<Au>,
     /// Whether the absolute containing block forces positioned descendants to be layerized.
     layers_needed_for_positioned_flows: bool,
diff --git a/src/components/main/layout/inline.rs b/src/components/main/layout/inline.rs
index e162a270651..4c3e10fc265 100644
--- a/src/components/main/layout/inline.rs
+++ b/src/components/main/layout/inline.rs
@@ -495,7 +495,7 @@ impl InlineFlow {
         debug!("Flow: building display list for {:u} inline boxes", self.boxes.len());
 
         for box_ in self.boxes.iter() {
-            let rel_offset: Point2D<Au> = box_.relative_position(&info.containing_block_size);
+            let rel_offset = box_.relative_position(&info.relative_containing_block_size);
             box_.build_display_list(stacking_context,
                                     builder,
                                     info,
diff --git a/src/components/main/layout/layout_task.rs b/src/components/main/layout/layout_task.rs
index 1e338bd7e1c..267da50e62b 100644
--- a/src/components/main/layout/layout_task.rs
+++ b/src/components/main/layout/layout_task.rs
@@ -634,7 +634,7 @@ impl LayoutTask {
                     dirty: flow::base(layout_root).position.clone(),
                 };
                 let display_list_building_info = DisplayListBuildingInfo {
-                    containing_block_size: flow::base(layout_root).position.size,
+                    relative_containing_block_size: flow::base(layout_root).position.size,
                     absolute_containing_block_position: Point2D(Au(0), Au(0)),
                     layers_needed_for_positioned_flows: false,
                 };
@@ -672,10 +672,10 @@ impl LayoutTask {
                     }
                 }
 
-                let root_size = Size2D(display_list_building_info.containing_block_size
+                let root_size = Size2D(display_list_building_info.relative_containing_block_size
                                                                  .width
                                                                  .to_nearest_px() as uint,
-                                       display_list_building_info.containing_block_size
+                                       display_list_building_info.relative_containing_block_size
                                                                  .height
                                                                  .to_nearest_px() as uint);
                 let render_layer = RenderLayer {