Even empty block intervals should be associated with a fragmentainer.

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

Index: third_party/WebKit/Source/core/layout/FragmentainerIterator.cpp
diff --git a/third_party/WebKit/Source/core/layout/FragmentainerIterator.cpp b/third_party/WebKit/Source/core/layout/FragmentainerIterator.cpp
index 61a3c8e89703670d03841cb34e539f5f0f108f27..50f2d0019e24a6ca5d675e68347d52430b07e053 100644
--- a/third_party/WebKit/Source/core/layout/FragmentainerIterator.cpp
+++ b/third_party/WebKit/Source/core/layout/FragmentainerIterator.cpp
@@ -32,9 +32,7 @@ FragmentainerIterator::FragmentainerIterator(
   // Jump to the first interesting column set.

[szager1, 2016/12/21 23:47:11]

This comment seems obsolete.

[mstensho (USE GERRIT), 2016/12/22 08:10:26]

Not really. We're still picking a column set based on the flow thread range
start.

   m_currentColumnSet = flowThread.columnSetAtBlockOffset(
       m_logicalTopInFlowThread, LayoutBox::AssociateWithLatterPage);
-  if (!m_currentColumnSet ||
-      m_currentColumnSet->logicalTopInFlowThread() >=
-          m_logicalBottomInFlowThread) {
+  if (!m_currentColumnSet) {
     setAtEnd();
     return;
   }