layout: Explicitly thread border box dimensions and relative offsets

through display list building.

The old `flow_origin` concept was ill-defined (sometimes the border box
plus the flow origin, sometimes including horizontal margins and
sometimes not, sometimes including relative position and sometimes not),
leading to brittleness and test failures. This commit reworks the logic
to always pass border box origins in during display list building.

components/layout/construct.rs

@@ -52,9 +52,9 @@ use servo_util::opts;
 use std::collections::DList;
 use std::mem;
 use std::sync::atomic::Relaxed;
-use style::ComputedValues;
 use style::computed_values::{caption_side, display, empty_cells, float, list_style_position};
 use style::computed_values::{position};
+use style::{mod, ComputedValues};
 use sync::Arc;
 use url::Url;
 
@@ -681,7 +681,7 @@ impl<'a> FlowConstructor<'a> {
     /// doesn't render its children, so this just nukes a child's fragments and creates a
     /// `Fragment`.
     fn build_fragments_for_replaced_inline_content(&mut self, node: &ThreadSafeLayoutNode)
-                                               -> ConstructionResult {
+                                                   -> ConstructionResult {
         for kid in node.children() {
             kid.set_flow_construction_result(ConstructionResult::None)
         }
@@ -697,24 +697,42 @@ impl<'a> FlowConstructor<'a> {
                 node.restyle_damage()))
         }
 
+        // If the value of `display` property is not `inline`, then we have a situation like
+        // `<div style="position:absolute">foo bar baz</div>`. The fragments for `foo`, `bar`, and
+        // `baz` had better not be absolutely positioned!
+        let mut style = (*node.style()).clone();
+        if style.get_box().display != display::inline {
+            style = Arc::new(style::make_inline(&*style))
+        }
+
         // If this is generated content, then we need to initialize the accumulator with the
         // fragment corresponding to that content. Otherwise, just initialize with the ordinary
         // fragment that needs to be generated for this inline node.
         let fragment = if node.get_pseudo_element_type() != PseudoElementType::Normal {
-            let fragment_info = SpecificFragmentInfo::UnscannedText(UnscannedTextFragmentInfo::new(node));
-            Fragment::new_from_specific_info(node, fragment_info)
+            let fragment_info =
+                SpecificFragmentInfo::UnscannedText(UnscannedTextFragmentInfo::new(node));
+            Fragment::from_opaque_node_and_style(
+                OpaqueNodeMethods::from_thread_safe_layout_node(node),
+                style,
+                node.restyle_damage(),
+                fragment_info)
         } else {
-            Fragment::new(self, node)
+            Fragment::from_opaque_node_and_style(
+                OpaqueNodeMethods::from_thread_safe_layout_node(node),
+                style,
+                node.restyle_damage(),
+                self.build_specific_fragment_info_for_node(node))
         };
 
         let mut fragments = DList::new();
         fragments.push_back(fragment);
 
-        let construction_item = ConstructionItem::InlineFragments(InlineFragmentsConstructionResult {
-            splits: DList::new(),
-            fragments: fragments,
-            abs_descendants: Descendants::new(),
-        });
+        let construction_item =
+            ConstructionItem::InlineFragments(InlineFragmentsConstructionResult {
+                splits: DList::new(),
+                fragments: fragments,
+                abs_descendants: Descendants::new(),
+            });
         ConstructionResult::ConstructionItem(construction_item)
     }
 
@@ -726,17 +744,19 @@ impl<'a> FlowConstructor<'a> {
             _ => unreachable!()
         };
 
-        let fragment_info = SpecificFragmentInfo::InlineBlock(InlineBlockFragmentInfo::new(block_flow));
+        let fragment_info = SpecificFragmentInfo::InlineBlock(InlineBlockFragmentInfo::new(
+                block_flow));
         let fragment = Fragment::new_from_specific_info(node, fragment_info);
 
         let mut fragment_accumulator = InlineFragmentsAccumulator::from_inline_node(node);
         fragment_accumulator.fragments.push_back(fragment);
 
-        let construction_item = ConstructionItem::InlineFragments(InlineFragmentsConstructionResult {
-            splits: DList::new(),
-            fragments: fragment_accumulator.to_dlist(),
-            abs_descendants: abs_descendants,
-        });
+        let construction_item =
+            ConstructionItem::InlineFragments(InlineFragmentsConstructionResult {
+                splits: DList::new(),
+                fragments: fragment_accumulator.to_dlist(),
+                abs_descendants: abs_descendants,
+            });
         ConstructionResult::ConstructionItem(construction_item)
     }
 
@@ -757,11 +777,12 @@ impl<'a> FlowConstructor<'a> {
         let mut fragment_accumulator = InlineFragmentsAccumulator::from_inline_node(node);
         fragment_accumulator.fragments.push_back(fragment);
 
-        let construction_item = ConstructionItem::InlineFragments(InlineFragmentsConstructionResult {
-            splits: DList::new(),
-            fragments: fragment_accumulator.to_dlist(),
-            abs_descendants: abs_descendants,
-        });
+        let construction_item =
+            ConstructionItem::InlineFragments(InlineFragmentsConstructionResult {
+                splits: DList::new(),
+                fragments: fragment_accumulator.to_dlist(),
+                abs_descendants: abs_descendants,
+            });
         ConstructionResult::ConstructionItem(construction_item)
     }