diff --git a/layout/base/nsCSSFrameConstructor.cpp b/layout/base/nsCSSFrameConstructor.cpp
index 81e1844a12f..56818d12832 100644
--- a/layout/base/nsCSSFrameConstructor.cpp
+++ b/layout/base/nsCSSFrameConstructor.cpp
@@ -7615,15 +7615,24 @@ DoApplyRenderingChangeToTree(nsIFrame* aFrame,
                              nsChangeHint aChange);
 
 /**
- * This rect is relative to aFrame's parent
- */
+ * Sync views on aFrame and all of aFrame's descendants (following placeholders),
+ * if aChange has nsChangeHint_SyncFrameView.
+ * Calls DoApplyRenderingChangeToTree on all aFrame's out-of-flow descendants
+ * (following placeholders), if aChange has nsChangeHint_RepaintFrame.
+ * aFrame should be some combination of nsChangeHint_SyncFrameView and
+ * nsChangeHint_RepaintFrame and nsChangeHint_UpdateOpacityLayer, nothing else.
+*/
 static void
-UpdateViewsForTree(nsIFrame* aFrame,
-                   nsFrameManager* aFrameManager,
-                   nsChangeHint aChange)
+SyncViewsAndInvalidateDescendants(nsIFrame* aFrame,
+                                  nsFrameManager* aFrameManager,
+                                  nsChangeHint aChange)
 {
   NS_PRECONDITION(gInApplyRenderingChangeToTree,
                   "should only be called within ApplyRenderingChangeToTree");
+  NS_ASSERTION(aChange == (aChange & (nsChangeHint_RepaintFrame |
+                                      nsChangeHint_SyncFrameView |
+                                      nsChangeHint_UpdateOpacityLayer)),
+               "Invalid change flag");
 
   nsView* view = aFrame->GetView();
   if (view) {
@@ -7652,7 +7661,7 @@ UpdateViewsForTree(nsIFrame* aFrame,
           DoApplyRenderingChangeToTree(child, aFrameManager,
                                        aChange);
         } else {  // regular frame
-          UpdateViewsForTree(child, aFrameManager, aChange);
+          SyncViewsAndInvalidateDescendants(child, aFrameManager, aChange);
         }
       }
     }
@@ -7709,18 +7718,15 @@ DoApplyRenderingChangeToTree(nsIFrame* aFrame,
                   "should only be called within ApplyRenderingChangeToTree");
 
   for ( ; aFrame; aFrame = nsLayoutUtils::GetNextContinuationOrSpecialSibling(aFrame)) {
-    // Get view if this frame has one and trigger an update. If the
-    // frame doesn't have a view, find the nearest containing view
-    // (adjusting r's coordinate system to reflect the nesting) and
-    // update there.
-    // We don't need to update transforms in UpdateViewsForTree, because
+    // Invalidate and sync views on all descendant frames, following placeholders.
+    // We don't need to update transforms in SyncViewsAndInvalidateDescendants, because
     // there can't be any out-of-flows or popups that need to be transformed;
     // all out-of-flow descendants of the transformed element must also be
     // descendants of the transformed frame.
-    UpdateViewsForTree(aFrame, aFrameManager,
-                       nsChangeHint(aChange & (nsChangeHint_RepaintFrame |
-                                               nsChangeHint_SyncFrameView |
-                                               nsChangeHint_UpdateOpacityLayer)));
+    SyncViewsAndInvalidateDescendants(aFrame, aFrameManager,
+      nsChangeHint(aChange & (nsChangeHint_RepaintFrame |
+                              nsChangeHint_SyncFrameView |
+                              nsChangeHint_UpdateOpacityLayer)));
     // This must be set to true if the rendering change needs to
     // invalidate content.  If it's false, a composite-only paint
     // (empty transaction) will be scheduled.