Even block flows with inline children must be examined when balancing columns.

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 
 #include "core/layout/ColumnBalancer.h"
 
 #include "core/layout/LayoutMultiColumnSet.h"
 
@@ skipping 15 matching lines @@
     if (box.childrenInline() && box.isLayoutBlockFlow()) {
         // Look for breaks between lines.
         for (const RootInlineBox* line = toLayoutBlockFlow(box).firstRootBox(); line; line = line->nextRootBox()) {
             LayoutUnit lineTopInFlowThread = m_flowThreadOffset + line->lineTopWithLeading();
             if (lineTopInFlowThread < group().logicalTopInFlowThread())
                 continue;
             if (lineTopInFlowThread >= group().logicalBottomInFlowThread())
                 break;
             examineLine(*line);
         }
-        return;
     }
 
     const LayoutFlowThread* flowThread = group().columnSet().flowThread();
     bool isHorizontalWritingMode = flowThread->isHorizontalWritingMode();
 
-    // Look for breaks between and inside children.
+    // Look for breaks between and inside block-level children. Even if this is a block flow with
+    // inline children, there may be interesting floats to examine here.
     for (const LayoutObject* child = box.slowFirstChild(); child; child = child->nextSibling()) {
-        if (!child->isBox())
+        if (!child->isBox() || child->isInline())
             continue;
         const LayoutBox& childBox = toLayoutBox(*child);
         LayoutRect overflowRect = childBox.layoutOverflowRect();
         LayoutUnit childLogicalBottomWithOverflow = childBox.logicalTop() + (isHorizontalWritingMode ? overflowRect.maxY() : overflowRect.maxX());
         if (m_flowThreadOffset + childLogicalBottomWithOverflow <= group().logicalTopInFlowThread()) {
             // This child is fully above the fragmentainer group we're examining.
             continue;
         }
         LayoutUnit childLogicalTopWithOverflow = childBox.logicalTop() + (isHorizontalWritingMode ? overflowRect.y() : overflowRect.x());
         if (m_flowThreadOffset + childLogicalTopWithOverflow >= group().logicalBottomInFlowThread()) {
@@ skipping 180 matching lines @@
         recordSpaceShortage(logicalOffsetFromCurrentColumn + lineHeight - m_pendingStrut);
         m_pendingStrut = LayoutUnit::min();
         return;
     }
     ASSERT(isFirstAfterBreak(lineTopInFlowThread) || !line.paginationStrut());
     if (isFirstAfterBreak(lineTopInFlowThread))
         recordSpaceShortage(lineHeight - line.paginationStrut());
 }
 
 } // namespace blink