Fix regression in page_cycler_v2.tough_layout_cases

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

 /*
  * Copyright (C) 2013 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 673 matching lines @@
     // The logical top might be saturated for very large elements. Comparing
     // with the old logical top might then yield a false negative, as adding and
     // removing margins, borders etc. from a saturated number might yield
     // incorrect results. If this is the case, always mark for layout.
     mark_descendants_with_floats = true;
   } else if (!child.AvoidsFloats() || child.ShrinkToAvoidFloats()) {
     // If an element might be affected by the presence of floats, then always
     // mark it for layout.
     LayoutUnit lowest_float =
         std::max(previous_float_logical_bottom, LowestFloatLogicalBottom());
-    lowest_float = std::max(lowest_float, child.LowestFloatLogicalBottom());
     if (lowest_float > new_logical_top)
       mark_descendants_with_floats = true;
   }
 
   if (mark_descendants_with_floats)
     child.MarkAllDescendantsWithFloatsForLayout();
 }
 
 bool LayoutBlockFlow::PositionAndLayoutOnceIfNeeded(
     LayoutBox& child,
@@ skipping 3005 matching lines @@
   bool is_paginated = View()->GetLayoutState()->IsPaginated();
   if (is_paginated && !ChildrenInline()) {
     // Forced breaks are inserted at class A break points. Floats may be
     // affected by a break-after value on the previous in-flow sibling.
     if (LayoutBox* previous_in_flow_box = child.PreviousInFlowSiblingBox()) {
       logical_top_margin_edge = ApplyForcedBreak(
           logical_top_margin_edge, previous_in_flow_box->BreakAfter());
     }
   }
 
+  LayoutUnit old_logical_top = child.LogicalTop();
   if (child.NeedsLayout()) {
     if (is_paginated) {
       // Before we can lay out the float, we need to estimate a position for
       // it. In order to do that, we first need to know its block start margin.
       child.ComputeAndSetBlockDirectionMargins(this);
       LayoutUnit margin_before = MarginBeforeForChild(child);
 
       // We have found the highest possible position for the float, so we'll
       // lay out right there. Later on, we may be pushed further down by
       // adjacent floats which we don't fit beside, or pushed by fragmentation
@@ skipping 29 matching lines @@
   SetLogicalTopForChild(child, logical_top_margin_edge + margin_before);
 
   SubtreeLayoutScope layout_scope(child);
 
   // A new position may mean that we need to insert, move or remove breaks
   // inside the float. We may also need to lay out if we just ceased to be
   // fragmented, in order to remove pagination struts inside the child.
   MarkChildForPaginationRelayoutIfNeeded(child, layout_scope);
   child.LayoutIfNeeded();
 
+  // If negative margin pushes the child completely out of its old position
+  // mark for layout siblings that may have it in its float lists.
+  if (child.LogicalBottom() <= old_logical_top) {
+    LayoutObject* next = child.NextSibling();
+    if (next && next->IsLayoutBlockFlow()) {
+      LayoutBlockFlow* nextBlock = ToLayoutBlockFlow(next);
+      if (!nextBlock->AvoidsFloats() || nextBlock->ShrinkToAvoidFloats())
+        nextBlock->MarkAllDescendantsWithFloatsForLayout();
+    }
+  }
+
   if (is_paginated) {
     PaginatedContentWasLaidOut(child.LogicalBottom());
 
     // We may have to insert a break before the float.
     LayoutUnit new_logical_top_margin_edge =
         AdjustFloatLogicalTopForPagination(child, logical_top_margin_edge);
     if (logical_top_margin_edge != new_logical_top_margin_edge) {
       // We had already found a location for the float, but a soft
       // fragmentainer break then made us push it further down. This may affect
       // the inline position of the float (since we may no longer be beside the
@@ skipping 878 matching lines @@
   return LayoutBlock::InvalidatePaint(paint_invalidation_state);
 }
 
 void LayoutBlockFlow::InvalidateDisplayItemClients(
     PaintInvalidationReason invalidation_reason) const {
   BlockFlowPaintInvalidator(*this).InvalidateDisplayItemClients(
       invalidation_reason);
 }
 
 }  // namespace blink