Backed out changeset b10e6ba9cbdb because gecko part had to be backed out. r=backout on a CLOSED TREE

Backs out https://github.com/servo/servo/pull/17796

components/style/gecko/generated/bindings.rs

@@ -1047,9 +1047,8 @@ extern "C" {
      -> CSSPseudoElementType;
 }
 extern "C" {
-    pub fn Gecko_CalcStyleDifference(old_style: *const ServoStyleContext,
-                                     new_style: *const ServoStyleContext,
-                                     old_style_bits: u64,
+    pub fn Gecko_CalcStyleDifference(oldstyle: *mut nsStyleContext,
+                                     newstyle: ServoComputedValuesBorrowed,
                                      any_style_changed: *mut bool)
      -> nsChangeHint;
 }

components/style/gecko/restyle_damage.rs

@@ -48,14 +48,14 @@ impl GeckoRestyleDamage {
     /// accessed from layout.
     pub fn compute_style_difference(
         source: &nsStyleContext,
-        old_style: &ComputedValues,
-        new_style: &Arc<ComputedValues>,
+        new_style: &Arc<ComputedValues>
     ) -> StyleDifference {
+        // TODO(emilio): Const-ify this?
+        let context = source as *const nsStyleContext as *mut nsStyleContext;
         let mut any_style_changed: bool = false;
         let hint = unsafe {
-            bindings::Gecko_CalcStyleDifference(old_style.as_style_context(),
-                                                new_style.as_style_context(),
-                                                source.mBits,
+            bindings::Gecko_CalcStyleDifference(context,
+                                                &new_style,
                                                 &mut any_style_changed)
         };
         let change = if any_style_changed { StyleChange::Changed } else { StyleChange::Unchanged };