auto merge of #3640 : cgaebel/servo/incremental-flow-construction, r=pcwalton

This also hides the not-yet-working parts of incremental reflow behind a runtime
flag. As I get the failing reftests passing, I'll send pull requests for them one
by one.

2 files changed, 20 insertions, 0 deletions

diff --git a/components/layout/css/node_style.rs b/components/layout/css/node_style.rs
index 8512429442a..35bb1b1a8fa 100644
--- a/components/layout/css/node_style.rs
+++ b/components/layout/css/node_style.rs
@@ -14,6 +14,7 @@ use sync::Arc;
 /// Node mixin providing `style` method that returns a `NodeStyle`
 pub trait StyledNode {
     fn style<'a>(&'a self) -> &'a Arc<ComputedValues>;
+    fn unstyle(self);
     fn restyle_damage(self) -> RestyleDamage;
     fn set_restyle_damage(self, damage: RestyleDamage);
 }
@@ -24,6 +25,10 @@ impl<'ln> StyledNode for ThreadSafeLayoutNode<'ln> {
         self.get_css_select_results()
     }
 
+    fn unstyle(self) {
+        self.remove_css_select_results()
+    }
+
     fn restyle_damage(self) -> RestyleDamage {
         self.get_restyle_damage()
     }
diff --git a/components/layout/css/node_util.rs b/components/layout/css/node_util.rs
index 17d181b9937..c5268abf169 100644
--- a/components/layout/css/node_util.rs
+++ b/components/layout/css/node_util.rs
@@ -13,6 +13,7 @@ use sync::Arc;
 pub trait NodeUtil {
     fn get_css_select_results<'a>(&'a self) -> &'a Arc<ComputedValues>;
     fn have_css_select_results(&self) -> bool;
+    fn remove_css_select_results(self);
 
     fn get_restyle_damage(self) -> RestyleDamage;
     fn set_restyle_damage(self, damage: RestyleDamage);
@@ -60,6 +61,20 @@ impl<'ln> NodeUtil for ThreadSafeLayoutNode<'ln> {
         layout_data_ref.as_ref().unwrap().shared_data.style.is_some()
     }
 
+    fn remove_css_select_results(self) {
+        let mut layout_data_ref = self.mutate_layout_data();
+        let layout_data = layout_data_ref.as_mut().expect("no layout data");
+
+        let style =
+            match self.get_pseudo_element_type() {
+                Before(_) => &mut layout_data.data.before_style,
+                After (_) => &mut layout_data.data.after_style,
+                Normal    => &mut layout_data.shared_data.style,
+            };
+
+        *style = None;
+    }
+
     /// Get the description of how to account for recent style changes.
     /// This is a simple bitfield and fine to copy by value.
     fn get_restyle_damage(self) -> RestyleDamage {