diff --git a/content/base/public/nsIContent.h b/content/base/public/nsIContent.h
index 63f192f8af5..3171afd30a1 100644
--- a/content/base/public/nsIContent.h
+++ b/content/base/public/nsIContent.h
@@ -33,8 +33,8 @@ enum nsLinkState {
 
 // IID for the nsIContent interface
 #define NS_ICONTENT_IID \
-{ 0x8a8b4b1d, 0x72d8, 0x428e, \
- { 0x95, 0x75, 0xf9, 0x18, 0xba, 0xf6, 0x9e, 0xa1 } }
+{ 0Xf22c131c, 0Xc554, 0X4d06, \
+  { 0X81, 0Xac, 0X86, 0X64, 0X2f, 0X05, 0Xcc, 0X81 } }
 
 /**
  * A node of content in a document's content model. This interface
@@ -305,6 +305,12 @@ public:
     return mNodeInfo->Equals(aTag, kNameSpaceID_MathML);
   }
 
+  inline bool IsActiveChildrenElement() const
+  {
+    return mNodeInfo->Equals(nsGkAtoms::children, kNameSpaceID_XBL) &&
+           GetBindingParent();
+  }
+
   /**
    * Returns an atom holding the name of the attribute of type ID on
    * this content node (if applicable).  Returns null for non-element
diff --git a/content/base/src/ChildIterator.cpp b/content/base/src/ChildIterator.cpp
index f3f43e517e3..fa83d891c57 100644
--- a/content/base/src/ChildIterator.cpp
+++ b/content/base/src/ChildIterator.cpp
@@ -16,7 +16,7 @@ ExplicitChildIterator::GetNextChild()
   // If we're already in the inserted-children array, look there first
   if (mIndexInInserted) {
     MOZ_ASSERT(mChild);
-    MOZ_ASSERT(mChild->NodeInfo()->Equals(nsGkAtoms::children, kNameSpaceID_XBL));
+    MOZ_ASSERT(mChild->IsActiveChildrenElement());
     MOZ_ASSERT(!mDefaultChild);
 
     XBLChildrenElement* point = static_cast<XBLChildrenElement*>(mChild);
@@ -28,7 +28,7 @@ ExplicitChildIterator::GetNextChild()
   } else if (mDefaultChild) {
     // If we're already in default content, check if there are more nodes there
     MOZ_ASSERT(mChild);
-    MOZ_ASSERT(mChild->NodeInfo()->Equals(nsGkAtoms::children, kNameSpaceID_XBL));
+    MOZ_ASSERT(mChild->IsActiveChildrenElement());
 
     mDefaultChild = mDefaultChild->GetNextSibling();
     if (mDefaultChild) {
@@ -44,8 +44,7 @@ ExplicitChildIterator::GetNextChild()
   }
 
   // Iterate until we find a non-<children>, or a <children> with content.
-  while (mChild &&
-         mChild->NodeInfo()->Equals(nsGkAtoms::children, kNameSpaceID_XBL)) {
+  while (mChild && mChild->IsActiveChildrenElement()) {
     XBLChildrenElement* point = static_cast<XBLChildrenElement*>(mChild);
     if (!point->mInsertedChildren.IsEmpty()) {
       mIndexInInserted = 1;
@@ -85,6 +84,7 @@ FlattenedChildIterator::FlattenedChildIterator(nsIContent* aParent)
          child;
          child = child->GetNextSibling()) {
       if (child->NodeInfo()->Equals(nsGkAtoms::children, kNameSpaceID_XBL)) {
+        MOZ_ASSERT(child->GetBindingParent());
         mXBLInvolved = true;
         break;
       }
@@ -131,8 +131,7 @@ nsIContent* FlattenedChildIterator::GetPreviousChild()
   }
 
   // Iterate until we find a non-<children>, or a <children> with content.
-  while (mChild &&
-         mChild->NodeInfo()->Equals(nsGkAtoms::children, kNameSpaceID_XBL)) {
+  while (mChild && mChild->IsActiveChildrenElement()) {
     XBLChildrenElement* point = static_cast<XBLChildrenElement*>(mChild);
     if (!point->mInsertedChildren.IsEmpty()) {
       mIndexInInserted = point->InsertedChildrenLength();
diff --git a/layout/base/nsCSSFrameConstructor.cpp b/layout/base/nsCSSFrameConstructor.cpp
index d631f9560be..9d4902d81fc 100644
--- a/layout/base/nsCSSFrameConstructor.cpp
+++ b/layout/base/nsCSSFrameConstructor.cpp
@@ -3518,7 +3518,7 @@ nsCSSFrameConstructor::ConstructFrameFromItemInternal(FrameConstructionItem& aIt
   // descendants.
   nsIContent* parent = content->GetParent();
   bool pushInsertionPoint = aState.mTreeMatchContext.mAncestorFilter.HasFilter() &&
-    parent && parent->NodeInfo()->Equals(nsGkAtoms::children, kNameSpaceID_XBL);
+    parent && parent->IsActiveChildrenElement();
   TreeMatchContext::AutoAncestorPusher
     insertionPointPusher(pushInsertionPoint,
                          aState.mTreeMatchContext,
@@ -6511,7 +6511,7 @@ nsCSSFrameConstructor::ContentAppended(nsIContent*     aContainer,
   nsIFrame* parentFrame = GetFrameFor(aContainer);
 
   // See comment in ContentRangeInserted for why this is necessary.
-  if (!parentFrame && !aContainer->NodeInfo()->Equals(nsGkAtoms::children, kNameSpaceID_XBL)) {
+  if (!parentFrame && !aContainer->IsActiveChildrenElement()) {
     return NS_OK;
   }
 
@@ -6934,7 +6934,7 @@ nsCSSFrameConstructor::ContentRangeInserted(nsIContent*            aContainer,
   // The xbl:children element won't have a frame, but default content can have the children as
   // a parent. While its uncommon to change the structure of the default content itself, a label,
   // for example, can be reframed by having its value attribute set or removed.
-  if (!parentFrame && !aContainer->NodeInfo()->Equals(nsGkAtoms::children, kNameSpaceID_XBL)) {
+  if (!parentFrame && !aContainer->IsActiveChildrenElement()) {
     return NS_OK;
   }
 
diff --git a/layout/base/nsFrameManager.cpp b/layout/base/nsFrameManager.cpp
index a61fbdcbf46..e23efc50826 100644
--- a/layout/base/nsFrameManager.cpp
+++ b/layout/base/nsFrameManager.cpp
@@ -1379,8 +1379,7 @@ nsFrameManager::ReResolveStyleContext(nsPresContext     *aPresContext,
         // children element. Push the children element as an ancestor here because it does
         // not have a frame and would not otherwise be pushed as an ancestor.
         nsIContent* parent = undisplayed->mContent->GetParent();
-        bool pushInsertionPoint = parent &&
-          parent->NodeInfo()->Equals(nsGkAtoms::children, kNameSpaceID_XBL);
+        bool pushInsertionPoint = parent && parent->IsActiveChildrenElement();
         TreeMatchContext::AutoAncestorPusher
           insertionPointPusher(pushInsertionPoint,
                                aTreeMatchContext,
@@ -1549,8 +1548,7 @@ nsFrameManager::ReResolveStyleContext(nsPresContext     *aPresContext,
             // Check if the frame has a content because |child| may be a nsPageFrame that does
             // not have a content.
             nsIContent* parent = child->GetContent() ? child->GetContent()->GetParent() : nullptr;
-            bool pushInsertionPoint = parent &&
-              parent->NodeInfo()->Equals(nsGkAtoms::children, kNameSpaceID_XBL);
+            bool pushInsertionPoint = parent && parent->IsActiveChildrenElement();
             TreeMatchContext::AutoAncestorPusher
               insertionPointPusher(pushInsertionPoint, aTreeMatchContext,
                                    parent && parent->IsElement() ? parent->AsElement() : nullptr);
@@ -1911,8 +1909,7 @@ nsFrameManagerBase::UndisplayedMap::GetEntryFor(nsIContent** aParentContent)
   // be a <xbl:children> element) but the parent in the frame tree would be the
   // insertion parent (parent of the <xbl:children> element). Here the children
   // elements are normalized to the insertion parent to correct for the mismatch.
-  if (parentContent &&
-      parentContent->NodeInfo()->Equals(nsGkAtoms::children, kNameSpaceID_XBL)) {
+  if (parentContent && parentContent->IsActiveChildrenElement()) {
     parentContent = parentContent->GetParent();
     // Change the caller's pointer for the parent content to be the insertion parent.
     *aParentContent = parentContent;
diff --git a/layout/style/nsCSSRuleProcessor.cpp b/layout/style/nsCSSRuleProcessor.cpp
index f961205184e..ec16e670b86 100644
--- a/layout/style/nsCSSRuleProcessor.cpp
+++ b/layout/style/nsCSSRuleProcessor.cpp
@@ -2312,9 +2312,7 @@ static bool SelectorMatchesTree(Element* aPrevElement,
         // <xbl:children> element wasn't in the tree to allow old selectors
         // were written before <xbl:children> participated in CSS selector
         // matching to work.
-        if (selector->mOperator == '>' &&
-            element->NodeInfo()->Equals(nsGkAtoms::children,
-                                        kNameSpaceID_XBL)) {
+        if (selector->mOperator == '>' && element->IsActiveChildrenElement()) {
           Element* styleScope = aTreeMatchContext.mCurrentStyleScope;
           if (SelectorMatchesTree(element, selector, aTreeMatchContext,
                                   aLookForRelevantLink)) {