A new LayoutState should never locate a containing flow thread on its own.

third_party/WebKit/Source/core/layout/LayoutState.cpp

Index: third_party/WebKit/Source/core/layout/LayoutState.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutState.cpp b/third_party/WebKit/Source/core/layout/LayoutState.cpp
index 1ce3be9d14f3098b7dbb462cf78ffb158c2dfac4..8e9f3cd362814851e5d3c4aed75f382201a12841 100644
--- a/third_party/WebKit/Source/core/layout/LayoutState.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutState.cpp
@@ -95,10 +95,11 @@ LayoutState::LayoutState(LayoutBox& layoutObject, const LayoutSize& offset, Layo
         // Disable pagination for objects we don't support. For now this includes overflow:scroll/auto, inline blocks and
         // writing mode roots.
         if (layoutObject.isUnsplittableForPagination()) {
+            m_flowThread = nullptr;
             m_pageLogicalHeight = 0;
             m_isPaginated = false;
         } else {
-            m_isPaginated = m_pageLogicalHeight || layoutObject.flowThreadContainingBlock();
+            m_isPaginated = m_pageLogicalHeight || m_flowThread;
         }
     }