InitialColumnHeightFinder needs to take all expected rows into account.

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

Index: third_party/WebKit/Source/core/layout/LayoutMultiColumnSet.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutMultiColumnSet.cpp b/third_party/WebKit/Source/core/layout/LayoutMultiColumnSet.cpp
index 489b429c5f4596364b4d994aa762a347689cdd81..7d251344bb3c5ea25451bd41e06cfeb678ccf201 100644
--- a/third_party/WebKit/Source/core/layout/LayoutMultiColumnSet.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutMultiColumnSet.cpp
@@ -164,6 +164,26 @@ bool LayoutMultiColumnSet::isPageLogicalHeightKnown() const {
   return firstFragmentainerGroup().logicalHeight();
 }
 
+bool LayoutMultiColumnSet::newFragmentainerGroupsAllowed() const {
+  if (!isPageLogicalHeightKnown()) {
+    // If we have no clue about the height of the multicol container, bail. This
+    // situation occurs initially when an auto-height multicol container is
+    // nested inside another auto-height multicol container. We need at least an
+    // estimated height of the outer multicol container before we can check what
+    // an inner fragmentainer group has room for.
+    // Its height is indefinite for now.
+    return false;
+  }
+  if (isInitialHeightCalculated()) {
+    // We only insert additional fragmentainer groups in the initial layout
+    // pass. We only want to balance columns in the last fragmentainer group (if
+    // we need to balance at all), so we want that last fragmentainer group to
+    // be the same one in all layout passes that follow.
+    return false;
+  }
+  return true;
+}
+
 LayoutUnit LayoutMultiColumnSet::nextLogicalTopForUnbreakableContent(
     LayoutUnit flowThreadOffset,
     LayoutUnit contentLogicalHeight) const {