--- a/dom/base/nsIDocumentInlines.h
+++ b/dom/base/nsIDocumentInlines.h
@@ -59,16 +59,20 @@ 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(!mServoRestyleRoot ||
              mServoRestyleRoot == aRoot ||
              nsContentUtils::ContentIsFlattenedTreeDescendantOfForStyle(mServoRestyleRoot, aRoot));
   MOZ_ASSERT(aRoot == aRoot->OwnerDocAsNode() ||
              (aRoot->IsElement() && aRoot->IsInComposedDoc()));
   mServoRestyleRoot = aRoot;
   mServoRestyleRootDirtyBits = aDirtyBits;