Allow assertions to be enabled in Blink Release builds.

Source/core/rendering/RenderMultiColumnSet.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 113 matching lines @@
             largestHeight = height;
             indexWithLargestHeight = i;
         }
         previousOffset = run.breakOffset();
     }
     return indexWithLargestHeight;
 }
 
 void RenderMultiColumnSet::distributeImplicitBreaks()
 {
-#ifndef NDEBUG
+#if ENABLE(ASSERT)
     // There should be no implicit breaks assumed at this point.
     for (unsigned i = 0; i < m_contentRuns.size(); i++)
         ASSERT(!m_contentRuns[i].assumedImplicitBreaks());
-#endif // NDEBUG
+#endif // ENABLE(ASSERT)
 
     // Insert a final content run to encompass all content. This will include overflow if this is
     // the last set.
     addContentRun(logicalBottomInFlowThread());
     unsigned columnCount = m_contentRuns.size();
 
     // If there is room for more breaks (to reach the used value of column-count), imagine that we
     // insert implicit breaks at suitable locations. At any given time, the content run with the
     // currently tallest columns will get another implicit break "inserted", which will increase its
     // column count by one and shrink its columns' height. Repeat until we have the desired total
@@ skipping 538 matching lines @@
 
 void RenderMultiColumnSet::detachRegion()
 {
     if (m_flowThread) {
         m_flowThread->removeRegionFromThread(this);
         m_flowThread = 0;
     }
 }
 
 }