--- a/layout/base/nsCSSFrameConstructor.cpp
+++ b/layout/base/nsCSSFrameConstructor.cpp
@@ -7107,29 +7107,28 @@ nsCSSFrameConstructor::ContentAppended(n
     // construction case, except when we're already constructing frames, in
     // which case we shouldn't need to do anything else.
     if (aInsertionKind == InsertionKind::Async) {
       LazilyStyleNewChildRange(aFirstNewContent, nullptr);
     }
     return;
   }
 
-  if (aInsertionKind == InsertionKind::Async &&
-      MaybeConstructLazily(CONTENTAPPEND, aFirstNewContent)) {
-    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) {
+    if (MaybeConstructLazily(CONTENTAPPEND, aFirstNewContent)) {
+      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).
     StyleNewChildRange(aFirstNewContent, nullptr);
   }
 
+
   LAYOUT_PHASE_TEMP_EXIT();
   if (MaybeRecreateForFrameset(parentFrame, aFirstNewContent, nullptr)) {
     LAYOUT_PHASE_TEMP_REENTER();
     return;
   }
   LAYOUT_PHASE_TEMP_REENTER();
 
   if (parentFrame->IsLeaf()) {
@@ -7457,36 +7456,26 @@ nsCSSFrameConstructor::ContentRangeInser
     // XXX the GetContent() != child check is needed due to bug 135040.
     // Remove it once that's fixed.
     NS_ASSERTION(!child->GetPrimaryFrame() ||
                  child->GetPrimaryFrame()->GetContent() != child,
                  "asked to construct a frame for a node that already has a frame");
   }
 #endif
 
-  auto styleNewChildRangeEagerly =
-    [this, aInsertionKind, aStartChild, aEndChild]() {
-      // When aInsertionKind == InsertionKind::Sync, we know that the
-      // styles are up-to-date already.
-      if (aInsertionKind == InsertionKind::Async) {
-        StyleNewChildRange(aStartChild, aEndChild);
-      }
-    };
 
   bool isSingleInsert = (aStartChild->GetNextSibling() == aEndChild);
   NS_ASSERTION(isSingleInsert ||
                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 (aStartChild->GetParent() && IsXULListBox(aStartChild->GetParent())) {
-    // For XUL list box, we need to style the new children eagerly.
-    styleNewChildRangeEagerly();
     if (isSingleInsert) {
       // The insert case in NotifyListBoxBody doesn't use "old next sibling".
       if (NotifyListBoxBody(mPresShell->GetPresContext(),
                             aStartChild, nullptr, nullptr, CONTENT_INSERTED)) {
         return;
       }
     } else {
       // We don't handle a range insert to a listbox parent, issue single
@@ -7562,25 +7551,26 @@ nsCSSFrameConstructor::ContentRangeInser
     // construction case, except when we're already constructing frames, in
     // which case we shouldn't need to do anything else.
     if (aInsertionKind == InsertionKind::Async) {
       LazilyStyleNewChildRange(aStartChild, aEndChild);
     }
     return;
   }
 
-  if (aInsertionKind == InsertionKind::Async &&
-      MaybeConstructLazily(CONTENTINSERT, aStartChild)) {
-    LazilyStyleNewChildRange(aStartChild, aEndChild);
-    return;
-  }
-
-  // We couldn't construct lazily. Make Servo eagerly traverse the new content
-  // if needed.
-  styleNewChildRangeEagerly();
+  if (aInsertionKind == InsertionKind::Async) {
+    if (MaybeConstructLazily(CONTENTINSERT, aStartChild)) {
+      LazilyStyleNewChildRange(aStartChild, aEndChild);
+      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).
+    StyleNewChildRange(aStartChild, aEndChild);
+  }
 
   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
@@ -11153,16 +11143,20 @@ nsCSSFrameConstructor::CreateListBoxCont
   if (aParentFrame) {
     nsFrameItems            frameItems;
     nsFrameConstructorState state(mPresShell,
                                   GetAbsoluteContainingBlock(aParentFrame, FIXED_POS),
                                   GetAbsoluteContainingBlock(aParentFrame, ABS_POS),
                                   GetFloatContainingBlock(aParentFrame),
                                   do_AddRef(mTempFrameTreeState));
 
+    if (aChild->IsElement() && !aChild->AsElement()->HasServoData()) {
+      mPresShell->StyleSet()->StyleNewSubtree(aChild->AsElement());
+    }
+
     RefPtr<ComputedStyle> computedStyle = ResolveComputedStyle(aChild);
 
     // Pre-check for display "none" - only if we find that, do we create
     // any frame at all
     const nsStyleDisplay* display = computedStyle->StyleDisplay();
 
     if (StyleDisplay::None == display->mDisplay) {
       *aNewFrame = nullptr;