Only the first layout pass needs to go deep when pagination state changes.

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 390 matching lines @@
 
   LayoutAnalyzer::BlockScope analyzer(*this);
   SubtreeLayoutScope layoutScope(*this);
 
   LayoutUnit previousHeight = logicalHeight();
   LayoutUnit oldLeft = logicalLeft();
   bool logicalWidthChanged = updateLogicalWidthAndColumnWidth();
   relayoutChildren |= logicalWidthChanged;
 
   TextAutosizer::LayoutScope textAutosizerLayoutScope(this, &layoutScope);
-  LayoutState state(*this, logicalWidthChanged);
 
-  if (m_paginationStateChanged) {
-    // We now need a deep layout to clean up struts after pagination, if we
-    // just ceased to be paginated, or, if we just became paginated on the
-    // other hand, we now need the deep layout, to insert pagination struts.
-    m_paginationStateChanged = false;
-    state.setPaginationStateChanged();
-  }
-
+  bool paginationStateChanged = m_paginationStateChanged;
   bool preferredLogicalWidthsWereDirty = preferredLogicalWidthsDirty();
 
   // Multiple passes might be required for column based layout.
   // The number of passes could be as high as the number of columns.
   LayoutMultiColumnFlowThread* flowThread = multiColumnFlowThread();
   do {
+    LayoutState state(*this, logicalWidthChanged);
+    if (m_paginationStateChanged) {
+      // We now need a deep layout to clean up struts after pagination, if we
+      // just ceased to be paginated, or, if we just became paginated on the
+      // other hand, we now need the deep layout, to insert pagination struts.
+      m_paginationStateChanged = false;
+      state.setPaginationStateChanged();
+    }
+
     layoutChildren(relayoutChildren, layoutScope);
 
     if (!preferredLogicalWidthsWereDirty && preferredLogicalWidthsDirty()) {
       // The only thing that should dirty preferred widths at this point is the
       // addition of overflow:auto scrollbars in a descendant. To avoid a
       // potential infinite loop, run layout again with auto scrollbars frozen
       // in their current state.
       PaintLayerScrollableArea::FreezeScrollbarsScope freezeScrollbars;
       relayoutChildren |= updateLogicalWidthAndColumnWidth();
       layoutChildren(relayoutChildren, layoutScope);
     }
 
     if (flowThread && flowThread->columnHeightsChanged()) {
       setChildNeedsLayout(MarkOnlyThis);
       continue;
     }
 
     if (shouldBreakAtLineToAvoidWidow()) {
       setEverHadLayout();
       continue;
     }
     break;
   } while (true);
 
+  LayoutState state(*this, logicalWidthChanged);
+  if (paginationStateChanged) {
+    // We still haven't laid out positioned descendants, and we need to perform
+    // a deep layout on those too if pagination state changed.
+    state.setPaginationStateChanged();
+  }
+
   // Remember the automatic logical height we got from laying out the children.
   LayoutUnit unconstrainedHeight = logicalHeight();
   LayoutUnit unconstrainedClientAfterEdge = clientLogicalBottom();
 
   // Adjust logical height to satisfy whatever computed style requires.
   updateLogicalHeight();
 
   if (!childrenInline())
     addOverhangingFloatsFromChildren(unconstrainedHeight);
 
@@ skipping 4107 matching lines @@
   return LayoutBlock::invalidatePaintIfNeeded(paintInvalidationState);
 }
 
 void LayoutBlockFlow::invalidateDisplayItemClients(
     PaintInvalidationReason invalidationReason) const {
   BlockFlowPaintInvalidator(*this).invalidateDisplayItemClients(
       invalidationReason);
 }
 
 }  // namespace blink