Allow setting id, class, style without a full reflow

Instead we do selector matching again, then diff the style structs to set the
"restyle damage" bits which are used to prune reflow traversals.

Also don't force a reflow when timers finish, because individual DOM methods
should already take care of that.

src/components/script/dom/document.rs

@@ -23,6 +23,7 @@ use dom::htmltitleelement::HTMLTitleElement;
 use html::hubbub_html_parser::build_element_from_tag;
 use js::jsapi::{JSObject, JSContext, JSTracer};
 use servo_util::tree::{TreeNodeRef, ElementLike};
+use layout_interface::{DocumentDamageLevel, ContentChangedDocumentDamage};
 
 use std::hashmap::HashMap;
 
@@ -319,7 +320,11 @@ impl Document {
     }
 
     pub fn content_changed(&self) {
-        self.window.content_changed();
+        self.damage_and_reflow(ContentChangedDocumentDamage);
+    }
+
+    pub fn damage_and_reflow(&self, damage: DocumentDamageLevel) {
+        self.window.damage_and_reflow(damage);
     }
 
     pub fn wait_until_safe_to_modify_dom(&self) {

src/components/script/dom/element.rs

@@ -18,7 +18,8 @@ use dom::document;
 use dom::namespace;
 use dom::namespace::Namespace;
 use layout_interface::{ContentBoxQuery, ContentBoxResponse, ContentBoxesQuery};
-use layout_interface::{ContentBoxesResponse};
+use layout_interface::{ContentBoxesResponse, ContentChangedDocumentDamage};
+use layout_interface::{MatchSelectorsDocumentDamage};
 use style;
 use servo_util::tree::{TreeNodeRef, ElementLike};
 
@@ -293,8 +294,12 @@ impl<'self> Element {
         }
 
         if abstract_self.is_in_doc() {
+            let damage = match local_name.as_slice() {
+                "style" | "id" | "class" => MatchSelectorsDocumentDamage,
+                _ => ContentChangedDocumentDamage
+            };
             let document = self.node.owner_doc();
-            document.document().content_changed();
+            document.document().damage_and_reflow(damage);
         }
     }
 }

src/components/script/dom/window.rs

@@ -12,7 +12,7 @@ use dom::node::{AbstractNode, ScriptView};
 use dom::location::Location;
 use dom::navigator::Navigator;
 
-use layout_interface::{ReflowForDisplay, ContentChangedDocumentDamage};
+use layout_interface::{ReflowForDisplay, DocumentDamageLevel};
 use script_task::{ExitWindowMsg, FireTimerMsg, Page, ScriptChan};
 use servo_msg::compositor_msg::ScriptListener;
 use servo_net::image_cache_task::ImageCacheTask;
@@ -185,11 +185,11 @@ impl Window {
         self.active_timers.remove(&handle);
     }
 
-    pub fn content_changed(&self) {
+    pub fn damage_and_reflow(&self, damage: DocumentDamageLevel) {
         // FIXME This should probably be ReflowForQuery, not Display. All queries currently
         // currently rely on the display list, which means we can't destroy it by
         // doing a query reflow.
-        self.page.damage(ContentChangedDocumentDamage);
+        self.page.damage(damage);
         self.page.reflow(ReflowForDisplay, self.script_chan.clone(), self.compositor);
     }
 

src/components/script/script_task.rs

@@ -588,9 +588,6 @@ impl ScriptTask {
                                  &rval);
 
         }
-        // We don't know what the script changed, so for now we will do a total redisplay.
-        page.damage(ContentChangedDocumentDamage);
-        page.reflow(ReflowForDisplay, self.chan.clone(), self.compositor);
     }
 
     /// Handles a notification that reflow completed.