--- a/layout/base/nsCSSFrameConstructor.cpp
+++ b/layout/base/nsCSSFrameConstructor.cpp
@@ -7093,25 +7093,23 @@ IsSpecialFramesetChild(nsIContent* aCont
   return aContent->IsAnyOfHTMLElements(nsGkAtoms::frameset, nsGkAtoms::frame);
 }
 
 static void
 InvalidateCanvasIfNeeded(nsIPresShell* presShell, nsIContent* node);
 
 #ifdef MOZ_XUL
 
-static
-bool
+static bool
 IsXULListBox(nsIContent* aContainer)
 {
-  return (aContainer->IsXULElement(nsGkAtoms::listbox));
-}
-
-static
-nsListBoxBodyFrame*
+  return aContainer->IsXULElement(nsGkAtoms::listbox);
+}
+
+static nsListBoxBodyFrame*
 MaybeGetListBoxBodyFrame(nsIContent* aContainer, nsIContent* aChild)
 {
   if (!aContainer)
     return nullptr;
 
   if (IsXULListBox(aContainer) &&
       aChild->IsXULElement(nsGkAtoms::listitem)) {
     RefPtr<nsXULElement> xulElement = nsXULElement::FromContent(aContainer);
@@ -7578,32 +7576,32 @@ nsCSSFrameConstructor::ContentAppended(n
   if (aInsertionKind == InsertionKind::Async &&
       MaybeConstructLazily(CONTENTAPPEND, aContainer, aFirstNewContent)) {
     if (aContainer->IsStyledByServo()) {
       LazilyStyleNewChildRange(aFirstNewContent, nullptr);
     }
     return;
   }
 
-  // We couldn't construct lazily. Make Servo eagerly traverse the new content
-  // if needed (when aInsertionKind == InsertionKind::Sync, we know that the
-  // styles are up-to-date already).
-  if (aInsertionKind == InsertionKind::Async && aContainer->IsStyledByServo()) {
-    StyleNewChildRange(aFirstNewContent, nullptr);
-  }
-
   LAYOUT_PHASE_TEMP_EXIT();
   InsertionPoint insertion =
     GetRangeInsertionPoint(aContainer, aFirstNewContent, nullptr);
   nsContainerFrame*& parentFrame = insertion.mParentFrame;
   LAYOUT_PHASE_TEMP_REENTER();
   if (!parentFrame) {
     return;
   }
 
+  // We couldn't construct lazily. Make Servo eagerly traverse the new content
+  // if needed (when aInsertionKind == InsertionKind::Sync, we know that the
+  // styles are up-to-date already).
+  if (aInsertionKind == InsertionKind::Async && aContainer->IsStyledByServo()) {
+    StyleNewChildRange(aFirstNewContent, nullptr);
+  }
+
   LAYOUT_PHASE_TEMP_EXIT();
   if (MaybeRecreateForFrameset(parentFrame, aFirstNewContent, nullptr)) {
     LAYOUT_PHASE_TEMP_REENTER();
     return;
   }
   LAYOUT_PHASE_TEMP_REENTER();
 
   if (parentFrame->IsLeaf()) {
@@ -7835,52 +7833,42 @@ nsCSSFrameConstructor::ContentAppended(n
     accService->ContentRangeInserted(mPresShell, aContainer,
                                      aFirstNewContent, nullptr);
   }
 #endif
 }
 
 #ifdef MOZ_XUL
 
-enum content_operation
-{
-    CONTENT_INSERTED,
-    CONTENT_REMOVED
-};
-
 // Helper function to lookup the listbox body frame and send a notification
-// for insertion or removal of content
-static
-bool NotifyListBoxBody(nsPresContext*    aPresContext,
-                         nsIContent*        aContainer,
-                         nsIContent*        aChild,
-                         // Only used for the removed notification
-                         nsIContent*        aOldNextSibling,
-                         nsIFrame*          aChildFrame,
-                         content_operation  aOperation)
+// for removal of content.
+static bool
+MaybeNotifyListBoxBodyOfRemoval(nsPresContext* aPresContext,
+                                nsIContent* aContainer,
+                                nsIContent* aChild,
+                                nsIContent* aOldNextSibling,
+                                nsIFrame* aChildFrame)
 {
   nsListBoxBodyFrame* listBoxBodyFrame =
     MaybeGetListBoxBodyFrame(aContainer, aChild);
-  if (listBoxBodyFrame) {
-    if (aOperation == CONTENT_REMOVED) {
-      // Except if we have an aChildFrame and its parent is not the right
-      // thing, then we don't do this.  Pseudo frames are so much fun....
-      if (!aChildFrame || aChildFrame->GetParent() == listBoxBodyFrame) {
-        listBoxBodyFrame->OnContentRemoved(aPresContext, aContainer,
-                                           aChildFrame, aOldNextSibling);
-        return true;
-      }
-    } else {
-      listBoxBodyFrame->OnContentInserted(aChild);
-      return true;
-    }
-  }
-
-  return false;
-}
+  if (!listBoxBodyFrame) {
+    return false;
+  }
+
+  // Except if we have an aChildFrame and its parent is not the right
+  // thing, then we don't do this.  Pseudo frames are so much fun....
+  if (aChildFrame && aChildFrame->GetParent() != listBoxBodyFrame) {
+    return false;
+  }
+
+  listBoxBodyFrame->OnContentRemoved(
+    aPresContext, aContainer, aChildFrame, aOldNextSibling);
+  return true;
+}
+
 #endif // MOZ_XUL
 
 void
 nsCSSFrameConstructor::ContentInserted(nsIContent* aContainer,
                                        nsIContent* aChild,
                                        nsILayoutHistoryState* aFrameState,
                                        InsertionKind aInsertionKind)
 {
@@ -7969,22 +7957,21 @@ nsCSSFrameConstructor::ContentRangeInser
                aInsertionKind == InsertionKind::Sync,
                "range insert shouldn't be lazy");
   NS_ASSERTION(isSingleInsert || aEndChild,
                "range should not include all nodes after aStartChild");
 
 #ifdef MOZ_XUL
   if (aContainer && IsXULListBox(aContainer)) {
     // For XUL list box, we need to style the new children eagerly.
-    styleNewChildRangeEagerly();
     if (isSingleInsert) {
-      if (NotifyListBoxBody(mPresShell->GetPresContext(), aContainer,
-                            // The insert case in NotifyListBoxBody
-                            // doesn't use "old next sibling".
-                            aStartChild, nullptr, nullptr, CONTENT_INSERTED)) {
+      if (nsListBoxBodyFrame* listBoxBodyFrame =
+            MaybeGetListBoxBodyFrame(aContainer, aStartChild)) {
+        styleNewChildRangeEagerly();
+        listBoxBodyFrame->OnContentInserted(aStartChild);
         return;
       }
     } else {
       // We don't handle a range insert to a listbox parent, issue single
       // ContertInserted calls for each node inserted.
       LAYOUT_PHASE_TEMP_EXIT();
       IssueSingleInsertNofications(aContainer, aStartChild, aEndChild);
       LAYOUT_PHASE_TEMP_REENTER();
@@ -8063,20 +8050,16 @@ nsCSSFrameConstructor::ContentRangeInser
   if (aInsertionKind == InsertionKind::Async &&
       MaybeConstructLazily(CONTENTINSERT, aContainer, aStartChild)) {
     if (aContainer->IsStyledByServo()) {
       LazilyStyleNewChildRange(aStartChild, aEndChild);
     }
     return;
   }
 
-  // We couldn't construct lazily. Make Servo eagerly traverse the new content
-  // if needed.
-  styleNewChildRangeEagerly();
-
   InsertionPoint insertion;
   if (isSingleInsert) {
     // See if we have an XBL insertion point. If so, then that's our
     // real parent frame; if not, then the frame hasn't been built yet
     // and we just bail.
     insertion = GetInsertionPoint(aContainer, aStartChild);
   } else {
     // Get our insertion point. If we need to issue single ContentInserted's
@@ -8085,16 +8068,21 @@ nsCSSFrameConstructor::ContentRangeInser
     insertion = GetRangeInsertionPoint(aContainer, aStartChild, aEndChild);
     LAYOUT_PHASE_TEMP_REENTER();
   }
 
   if (!insertion.mParentFrame) {
     return;
   }
 
+  // We couldn't construct lazily.
+  //
+  // Make Servo eagerly traverse the new content if needed.
+  styleNewChildRangeEagerly();
+
   bool isAppend, isRangeInsertSafe;
   nsIFrame* prevSibling = GetInsertionPrevSibling(&insertion, aStartChild,
                                                   &isAppend, &isRangeInsertSafe);
 
   // check if range insert is safe
   if (!isSingleInsert && !isRangeInsertSafe) {
     // must fall back to a single ContertInserted for each child in the range
     LAYOUT_PHASE_TEMP_EXIT();
@@ -8521,18 +8509,18 @@ nsCSSFrameConstructor::ContentRemoved(ns
         }
       }
     }
     UnregisterDisplayContentsStyleFor(aChild, aContainer);
     return false;
   }
 
 #ifdef MOZ_XUL
-  if (NotifyListBoxBody(presContext, aContainer, aChild, aOldNextSibling,
-                        childFrame, CONTENT_REMOVED)) {
+  if (MaybeNotifyListBoxBodyOfRemoval(
+        presContext, aContainer, aChild, aOldNextSibling, childFrame)) {
     return false;
   }
 #endif // MOZ_XUL
 
   // If we're removing the root, then make sure to remove things starting at
   // the viewport's child instead of the primary frame (which might even be
   // null if the root had an XBL binding or display:none, even though the
   // frames above it got created).  We do the adjustment after the childFrame