ColumnBalancer: don't skip bounds checking on first or last fragmentainer groups.

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

 // 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 "core/layout/MultiColumnFragmentainerGroup.h"
 
 namespace blink {
 
 // A column balancer traverses the portion of the subtree of a flow thread that belongs to a given
 // fragmentainer group, in order to collect certain data to be used for column balancing. This is an
@@ skipping 15 matching lines @@
     {
         if (flowThreadOffset != m_group.columnLogicalTopForOffset(flowThreadOffset))
             return false; // Not at the top of a column.
         // The first column in the fragmentainer group is either not after any break at all, or
         // after a break that belongs to the previous fragmentainer group.
         return flowThreadOffset > m_group.logicalTopInFlowThread();
     }
 
     bool isLogicalTopWithinBounds(LayoutUnit logicalTopInFlowThread) const
     {
-        return (m_group.isFirstGroup() || logicalTopInFlowThread >= m_group.logicalTopInFlowThread())
-            && (m_group.isLastGroup() || logicalTopInFlowThread < m_group.logicalBottomInFlowThread());
+        return logicalTopInFlowThread >= m_group.logicalTopInFlowThread()
+            && logicalTopInFlowThread < m_group.logicalBottomInFlowThread();
     }
 
     bool isLogicalBottomWithinBounds(LayoutUnit logicalBottomInFlowThread) const
     {
-        return (m_group.isFirstGroup() || logicalBottomInFlowThread > m_group.logicalTopInFlowThread())
-            && (m_group.isLastGroup() || logicalBottomInFlowThread <= m_group.logicalBottomInFlowThread());
+        return logicalBottomInFlowThread > m_group.logicalTopInFlowThread()
+            && logicalBottomInFlowThread <= m_group.logicalBottomInFlowThread();
     }
 
     // Examine and collect column balancing data from a layout box that has been found to intersect
     // with this fragmentainer group. Does not recurse into children. flowThreadOffset() will
     // return the offset from |box| to the flow thread. Two hooks are provided here. The first one
     // is called right after entering and before traversing the subtree of the box, and the second
     // one right after having traversed the subtree.
     virtual void examineBoxAfterEntering(const LayoutBox&) = 0;
     virtual void examineBoxBeforeLeaving(const LayoutBox&) = 0;
 
@@ skipping 141 matching lines @@
     LayoutUnit m_minimumSpaceShortage;
 
     // Set when breaking before a block, and we're looking for the first unbreakable descendant, in
     // order to report correct space shortage for that one.
     LayoutUnit m_pendingStrut;
 
     unsigned m_forcedBreaksCount;
 };
 
 } // namespace blink