# HG changeset patch
# User Emilio Cobos Alvarez <emilio@crisal.io>
# Date 1519048452 -3600
# Node ID 577a507f9ee1b970382008c46d5402970eb82632
# Parent  dfd28d17636adfb0668fdb29b2e9ca73fdb965e3
Bug 1439016: Clear servo data on slot changes too. r=bholley

Pretty much the same way as what we do on XBL insertion point changes, since the
data would be stale.

I think both of those are kind of a hack, btw, and that we could fix it doing
ClearServoDataFromSubtree properly before we start unbinding. That'd prevent all
these issues, and all the complexity that entails receiving restyle requests
mid-unbind (we'd guarantee the tree is always in a stable state).

That's a matter of a different bug though.

MozReview-Commit-ID: Ev6RvGuPGiv

diff --git a/dom/base/FragmentOrElement.cpp b/dom/base/FragmentOrElement.cpp
--- a/dom/base/FragmentOrElement.cpp
+++ b/dom/base/FragmentOrElement.cpp
@@ -1128,17 +1128,25 @@ nsIContent::GetContainingShadowHost() co
     return shadow->GetHost();
   }
   return nullptr;
 }
 
 void
 nsIContent::SetAssignedSlot(HTMLSlotElement* aSlot)
 {
-  ExtendedContentSlots()->mAssignedSlot = aSlot;
+  MOZ_ASSERT(aSlot || GetExistingExtendedContentSlots());
+  nsExtendedContentSlots* slots = ExtendedContentSlots();
+
+  RefPtr<HTMLSlotElement> oldSlot = slots->mAssignedSlot.forget();
+  slots->mAssignedSlot = aSlot;
+
+  if (oldSlot != aSlot && IsElement() && AsElement()->HasServoData()) {
+    ServoRestyleManager::ClearServoDataFromSubtree(AsElement());
+  }
 }
 
 void
 nsIContent::SetXBLInsertionPoint(nsIContent* aContent)
 {
   nsCOMPtr<nsIContent> oldInsertionPoint = nullptr;
   if (aContent) {
     nsExtendedContentSlots* slots = ExtendedContentSlots();
@@ -1149,18 +1157,18 @@ nsIContent::SetXBLInsertionPoint(nsICont
     if (nsExtendedContentSlots* slots = GetExistingExtendedContentSlots()) {
       oldInsertionPoint = slots->mXBLInsertionPoint.forget();
       slots->mXBLInsertionPoint = nullptr;
     }
   }
 
   // We just changed the flattened tree, so any Servo style data is now invalid.
   // We rely on nsXBLService::LoadBindings to re-traverse the subtree afterwards.
-  if (oldInsertionPoint != aContent &&
-      IsStyledByServo() && IsElement() && AsElement()->HasServoData()) {
+  if (oldInsertionPoint != aContent && IsElement() &&
+      AsElement()->HasServoData()) {
     ServoRestyleManager::ClearServoDataFromSubtree(AsElement());
   }
 }
 
 nsresult
 FragmentOrElement::InsertChildAt(nsIContent* aKid,
                                 uint32_t aIndex,
                                 bool aNotify)