Soften assertion slightly, to survive saturated arithmetic situations.

third_party/WebKit/Source/core/layout/LayoutMultiColumnSet.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 81 matching lines @@
     return remainingLogicalHeight;
 }
 
 bool LayoutMultiColumnSet::isPageLogicalHeightKnown() const
 {
     return firstFragmentainerGroup().logicalHeight();
 }
 
 LayoutUnit LayoutMultiColumnSet::nextLogicalTopForUnbreakableContent(LayoutUnit flowThreadOffset, LayoutUnit contentLogicalHeight) const
 {
-    ASSERT(pageLogicalTopForOffset(flowThreadOffset) == flowThreadOffset);
+    ASSERT(flowThreadOffset.mightBeSaturated() || pageLogicalTopForOffset(flowThreadOffset) == flowThreadOffset);
     FragmentationContext* enclosingFragmentationContext = multiColumnFlowThread()->enclosingFragmentationContext();
     if (!enclosingFragmentationContext) {
         // If there's no enclosing fragmentation context, there'll ever be only one row, and all
         // columns there will have the same height.
         return flowThreadOffset;
     }
 
     // Assert the problematic situation. If we have no problem with the column height, why are we
     // even here?
     ASSERT(pageLogicalHeightForOffset(flowThreadOffset) < contentLogicalHeight);
@@ skipping 284 matching lines @@
 
 LayoutRect LayoutMultiColumnSet::flowThreadPortionRect() const
 {
     LayoutRect portionRect(LayoutUnit(), logicalTopInFlowThread(), pageLogicalWidth(), logicalHeightInFlowThread());
     if (!isHorizontalWritingMode())
         return portionRect.transposedRect();
     return portionRect;
 }
 
 }