Attempt to fix incremental layout

I have no idea how to test it,
but this code builds and is close enough to what it was befor #1109.

Review much needed.

src/components/main/css/matching.rs

@@ -6,6 +6,8 @@
 
 use std::cell::Cell;
 use css::node_style::StyledNode;
+use css::node_util::NodeUtil;
+use layout::incremental;
 
 use script::dom::node::{AbstractNode, LayoutView};
 use style::Stylist;
@@ -39,7 +41,7 @@ impl MatchMethods for AbstractNode<LayoutView> {
 
         for kid in self.children() {
             if kid.is_element() {
-                kid.match_subtree(stylist); 
+                kid.match_subtree(stylist);
             }
         }
     }
@@ -54,7 +56,15 @@ impl MatchMethods for AbstractNode<LayoutView> {
         };
         let cell = Cell::new(computed_values);
         do self.write_layout_data |data| {
-            data.style = Some(cell.take());
+            let style = cell.take();
+            // If there was an existing style, compute the damage that
+            // incremental layout will need to fix.
+            match data.style {
+                None => (),
+                Some(ref previous_style) => self.set_restyle_damage(
+                    incremental::compute_damage(previous_style, &style))
+            }
+            data.style = Some(style);
         }
     }
     fn cascade_subtree(&self, parent: Option<AbstractNode<LayoutView>>) {

src/components/main/layout/incremental.rs

@@ -2,9 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use newcss::complete::CompleteSelectResults;
+use style::ComputedValues;
-
-use script::dom::node::{AbstractNode, LayoutView};
 
 /// Individual layout actions that may be necessary after restyling.
 ///
@@ -113,18 +111,14 @@ impl RestyleDamage {
 // breakage on modifications.
 macro_rules! add_if_not_equal(
     ($old:ident, $new:ident, $damage:ident,
-     [ $($effect:ident),* ], [ $($getter:ident),* ]) => ({
+     [ $($effect:ident),* ], [ $($style_struct:ident.$name:ident),* ]) => ({
-        if $( ($old.$getter() != $new.$getter()) )||* {
+        if $( ($old.$style_struct.$name != $new.$style_struct.$name) )||* {
             $damage.union_in_place( restyle_damage!( $($effect),* ) );
         }
     })
 )
 
-pub fn compute_damage(node: &AbstractNode<LayoutView>,
+pub fn compute_damage(old: &ComputedValues, new: &ComputedValues) -> RestyleDamage {
-                      old_results: &CompleteSelectResults, new_results: &CompleteSelectResults)
-                      -> RestyleDamage {
-    let old = old_results.computed_style();
-    let new = new_results.computed_style();
     let mut damage = RestyleDamage::none();
 
     // This checks every CSS property, as enumerated in
@@ -134,21 +128,18 @@ pub fn compute_damage(node: &AbstractNode<LayoutView>,
     // FIXME: We can short-circuit more of this.
 
     add_if_not_equal!(old, new, damage, [ Repaint ],
-        [ color, background_color, border_top_color, border_right_color,
+        [ Color.color, Background.background_color,
-          border_bottom_color, border_left_color ]);
+          Border.border_top_color, Border.border_right_color,
+          Border.border_bottom_color, Border.border_left_color ]);
 
     add_if_not_equal!(old, new, damage, [ Repaint, BubbleWidths, Reflow ],
-        [ border_top_width, border_right_width, border_bottom_width,
+        [ Border.border_top_width, Border.border_right_width,
-          border_left_width, margin_top, margin_right, margin_bottom, margin_left,
+          Border.border_bottom_width, Border.border_left_width,
-          padding_top, padding_right, padding_bottom, padding_left, position,
+          Margin.margin_top, Margin.margin_right, Margin.margin_bottom, Margin.margin_left,
-          width, height, float, font_family, font_size, font_style, font_weight,
+          Padding.padding_top, Padding.padding_right, Padding.padding_bottom, Padding.padding_left,
-          text_align, text_decoration, line_height ]);
+          Box.position, Box.width, Box.height, Box.float, Box.display,
-
+          Font.font_family, Font.font_size, Font.font_style, Font.font_weight,
-    // Handle 'display' specially because it has this 'is_root' parameter.
+          Text.text_align, Text.text_decoration, Box.line_height ]);
-    let is_root = node.is_root();
-    if old.display(is_root) != new.display(is_root) {
-        damage.union_in_place(restyle_damage!(Repaint, BubbleWidths, Reflow));
-    }
 
     // FIXME: test somehow that we checked every CSS property