Migrate WTF::LinkedHashSet/ListHashSet::last() to ::back()

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

 /*
  * Copyright (C) 2012 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 454 matching lines @@
       return nullptr;
     if (offset < LayoutUnit()) {
       columnSet = m_multiColumnSetList.front();
     } else {
       MultiColumnSetSearchAdapter adapter(offset);
       m_multiColumnSetIntervalTree
           .allOverlapsWithAdapter<MultiColumnSetSearchAdapter>(adapter);
 
       // If no set was found, the offset is in the flow thread overflow.
       if (!adapter.result() && !m_multiColumnSetList.isEmpty())
-        columnSet = m_multiColumnSetList.last();
+        columnSet = m_multiColumnSetList.back();
       else
         columnSet = adapter.result();
     }
   }
   if (pageBoundaryRule == AssociateWithFormerPage && columnSet &&
       offset == columnSet->logicalTopInFlowThread()) {
     // The column set that we found starts at the exact same flow thread offset
     // as we specified. Since we are to associate offsets at boundaries with the
     // former fragmentainer, the fragmentainer we're looking for is in the
     // previous column set.
@@ skipping 890 matching lines @@
     const {
   return MultiColumnLayoutState(m_lastSetWorkedOn);
 }
 
 void LayoutMultiColumnFlowThread::restoreMultiColumnLayoutState(
     const MultiColumnLayoutState& state) {
   m_lastSetWorkedOn = state.columnSet();
 }
 
 }  // namespace blink