script: insert the restyle attribute restyle hint when a style attrib…

…ute is modified.

components/script/dom/document.rs

@@ -129,7 +129,7 @@ use std::sync::Arc;
 use std::time::{Duration, Instant};
 use style::attr::AttrValue;
 use style::context::{QuirksMode, ReflowGoal};
-use style::restyle_hints::RestyleHint;
+use style::restyle_hints::{RestyleHint, RESTYLE_STYLE_ATTRIBUTE};
 use style::selector_parser::{RestyleDamage, Snapshot};
 use style::str::{split_html_space_chars, str_join};
 use style::stylesheets::Stylesheet;
@@ -2142,23 +2142,32 @@ impl Document {
         RefMut::map(map, |m| m.entry(JS::from_ref(el)).or_insert_with(PendingRestyle::new))
     }
 
-    pub fn ensure_snapshot(&self, el: &Element) -> RefMut<Snapshot> {
+    pub fn element_state_will_change(&self, el: &Element) {
         let mut entry = self.ensure_pending_restyle(el);
         if entry.snapshot.is_none() {
             entry.snapshot = Some(Snapshot::new(el.html_element_in_html_document()));
         }
-        RefMut::map(entry, |e| e.snapshot.as_mut().unwrap())
-    }
-
-    pub fn element_state_will_change(&self, el: &Element) {
-        let mut snapshot = self.ensure_snapshot(el);
+        let mut snapshot = entry.snapshot.as_mut().unwrap();
         if snapshot.state.is_none() {
             snapshot.state = Some(el.state());
         }
     }
 
-    pub fn element_attr_will_change(&self, el: &Element, _attr: &Attr) {
-        let mut snapshot = self.ensure_snapshot(el);
+    pub fn element_attr_will_change(&self, el: &Element, attr: &Attr) {
+        // FIXME(emilio): Kind of a shame we have to duplicate this.
+        //
+        // I'm getting rid of the whole hashtable soon anyway, since all it does
+        // right now is populate the element restyle data in layout, and we
+        // could in theory do it in the DOM I think.
+        let mut entry = self.ensure_pending_restyle(el);
+        if entry.snapshot.is_none() {
+            entry.snapshot = Some(Snapshot::new(el.html_element_in_html_document()));
+        }
+        if attr.local_name() == &local_name!("style") {
+            entry.hint |= RESTYLE_STYLE_ATTRIBUTE;
+        }
+
+        let mut snapshot = entry.snapshot.as_mut().unwrap();
         if snapshot.attrs.is_none() {
             let attrs = el.attrs()
                           .iter()