--- a/dom/base/nsIDocumentInlines.h
+++ b/dom/base/nsIDocumentInlines.h
@@ -59,20 +59,17 @@ nsIDocument::FindDocStyleSheetInsertionP
 }
 
 inline void
 nsIDocument::SetServoRestyleRoot(nsINode* aRoot, uint32_t aDirtyBits)
 {
   MOZ_ASSERT(aRoot);
   MOZ_ASSERT(aDirtyBits);
   MOZ_ASSERT((aDirtyBits & ~Element::kAllServoDescendantBits) == 0);
-  // FIXME(emilio): This should hold, but we're clobbering it from
-  // nsCSSFrameConstructor::ConstructDocElementFrame, which is wrong!
-  //
-  // MOZ_ASSERT((aDirtyBits & mServoRestyleRootDirtyBits) == mServoRestyleRootDirtyBits);
+  MOZ_ASSERT((aDirtyBits & mServoRestyleRootDirtyBits) == mServoRestyleRootDirtyBits);
 
   MOZ_ASSERT(!mServoRestyleRoot ||
              mServoRestyleRoot == aRoot ||
              nsContentUtils::ContentIsFlattenedTreeDescendantOfForStyle(mServoRestyleRoot, aRoot));
   MOZ_ASSERT(aRoot == aRoot->OwnerDocAsNode() ||
              (aRoot->IsElement() && aRoot->IsInComposedDoc()));
   mServoRestyleRoot = aRoot;
   mServoRestyleRootDirtyBits = aDirtyBits;

--- a/layout/base/nsCSSFrameConstructor.cpp
+++ b/layout/base/nsCSSFrameConstructor.cpp
@@ -2544,23 +2544,23 @@ nsCSSFrameConstructor::ConstructDocEleme
   // have stale restyle bits from a previous frame constructor for
   // this document.  Unlike in AddFrameConstructionItems, it's safe to
   // unset all element restyle flags, since we don't have any
   // siblings.
   aDocElement->UnsetRestyleFlagsIfGecko();
 
   // --------- CREATE AREA OR BOX FRAME -------
   if (ServoStyleSet* set = mPresShell->StyleSet()->GetAsServo()) {
-    // We need to explicitly set a restyle root for the first traversal.
-    aDocElement->OwnerDoc()->SetServoRestyleRoot(aDocElement->OwnerDocAsNode(),
-                                                 ELEMENT_HAS_DIRTY_DESCENDANTS_FOR_SERVO);
-    // NOTE(emilio): If the root has a non-null binding, we'll stop at the
-    // document element and won't process any children, loading the bindings (or
-    // failing to do so) will take care of the rest.
-    set->StyleDocument(ServoTraversalFlags::Empty);
+    // Ensure the document element is styled at this point.
+    if (!aDocElement->HasServoData()) {
+      // NOTE(emilio): If the root has a non-null binding, we'll stop at the
+      // document element and won't process any children, loading the bindings
+      // (or failing to do so) will take care of the rest.
+      set->StyleNewSubtree(aDocElement);
+    }
   }
 
   // FIXME: Should this use ResolveStyleContext?  (The calls in this
   // function are the only case in nsCSSFrameConstructor where we don't
   // do so for the construction of a style context for an element.)
   RefPtr<nsStyleContext> styleContext =
     mPresShell->StyleSet()->ResolveStyleFor(aDocElement,
                                             nullptr,