Fix for ASSERTION FAILURE contentSize >=0

Source/core/layout/LayoutFlexibleBox.cpp

 /*
  * Copyright (C) 2011 Google 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:
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  *     * Redistributions of source code must retain the above copyright
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@@ skipping 99 matching lines @@
             maxPreferredLogicalWidth = child->maxPreferredLogicalWidth();
         }
         minPreferredLogicalWidth += margin;
         maxPreferredLogicalWidth += margin;
         if (!isColumnFlow()) {
             maxLogicalWidth += maxPreferredLogicalWidth;
             if (isMultiline()) {
                 // For multiline, the min preferred width is if you put a break between each item.
                 minLogicalWidth = std::max(minLogicalWidth, minPreferredLogicalWidth);
             } else {
-                minLogicalWidth += minPreferredLogicalWidth;
+                // We add minPreferredLogicalWidth only if is positive. Adding negative widths does not make sense.

[cbiesinger, 2015/05/27 16:50:19]

minPreferredLogicalWidth should not be negative. Why is it?

I feel like I saw another CL that tried to fix something like that... Ah: That
was https://codereview.chromium.org/343173003/, which is now committed. It seems
that a similar change needs to be applied to whichever LayoutObject returns a
negative number here.

+                if (minPreferredLogicalWidth >= 0)
+                    minLogicalWidth += minPreferredLogicalWidth;
             }
         } else {
             minLogicalWidth = std::max(minPreferredLogicalWidth, minLogicalWidth);
             maxLogicalWidth = std::max(maxPreferredLogicalWidth, maxLogicalWidth);
         }
     }
 
     maxLogicalWidth = std::max(minLogicalWidth, maxLogicalWidth);
 
     LayoutUnit scrollbarWidth = intrinsicScrollbarLogicalWidth();
@@ skipping 1326 matching lines @@
             ASSERT(child);
             LayoutUnit lineCrossAxisExtent = lineContexts[lineNumber].crossAxisExtent;
             LayoutUnit originalOffset = lineContexts[lineNumber].crossAxisOffset - crossAxisStartEdge;
             LayoutUnit newOffset = contentExtent - originalOffset - lineCrossAxisExtent;
             adjustAlignmentForChild(*child, newOffset - originalOffset);
         }
     }
 }
 
 }