Flexbox: negatively stretching a flexbox should have border + padding as a minimum

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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 1325 matching lines @@
         }
     }
 }
 
 void LayoutFlexibleBox::applyStretchAlignmentToChild(LayoutBox& child, LayoutUnit lineCrossAxisExtent)
 {
     if (!isColumnFlow() && child.style()->logicalHeight().isAuto()) {
         // FIXME: If the child has orthogonal flow, then it already has an override height set, so use it.
         if (!hasOrthogonalFlow(child)) {
             LayoutUnit heightBeforeStretching = needToStretchChildLogicalHeight(child) ? constrainedChildIntrinsicContentLogicalHeight(child) : child.logicalHeight();
-            LayoutUnit stretchedLogicalHeight = heightBeforeStretching + availableAlignmentSpaceForChildBeforeStretching(lineCrossAxisExtent, child);
+            LayoutUnit stretchedLogicalHeight = std::max(child.borderAndPaddingLogicalHeight(), heightBeforeStretching + availableAlignmentSpaceForChildBeforeStretching(lineCrossAxisExtent, child));
             ASSERT(!child.needsLayout());
             LayoutUnit desiredLogicalHeight = child.constrainLogicalHeightByMinMax(stretchedLogicalHeight, heightBeforeStretching - child.borderAndPaddingLogicalHeight());
 
             // FIXME: Can avoid laying out here in some cases. See https://webkit.org/b/87905.
             bool childNeedsRelayout = desiredLogicalHeight != child.logicalHeight();
             if (childNeedsRelayout || !child.hasOverrideHeight())
                 child.setOverrideLogicalContentHeight(desiredLogicalHeight - child.borderAndPaddingLogicalHeight());
             if (childNeedsRelayout) {
                 child.setLogicalHeight(0);
                 // We cache the child's intrinsic content logical height to avoid it being reset to the stretched height.
@@ skipping 44 matching lines @@
             ASSERT(child);
             LayoutUnit lineCrossAxisExtent = lineContexts[lineNumber].crossAxisExtent;
             LayoutUnit originalOffset = lineContexts[lineNumber].crossAxisOffset - crossAxisStartEdge;
             LayoutUnit newOffset = contentExtent - originalOffset - lineCrossAxisExtent;
             adjustAlignmentForChild(*child, newOffset - originalOffset);
         }
     }
 }
 
 }