Begin tracking why layout is invalidated

Source/core/layout/LayoutBlockFlowLine.cpp

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All right reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 1677 matching lines @@
                 break;
         }
         // Check if a new float has been inserted after the last known float.
         if (!curr && floatIndex < layoutState.floats().size())
             layoutState.markForFullLayout();
     }
 
     if (layoutState.isFullLayout()) {
         // If we encountered a new float and have inline children, mark ourself to force us to issue paint invalidations.
         if (layoutState.hasInlineChild() && !selfNeedsLayout()) {
-            setNeedsLayoutAndFullPaintInvalidation(MarkOnlyThis);
+            setNeedsLayoutAndFullPaintInvalidation(LayoutInvalidationReason::Unknown, MarkOnlyThis);

[esprehn, 2015/03/23 20:19:43]

This is from inside an already running layout

[pdr., 2015/03/24 03:56:18]

This should be okay. We have a similar situation with style recalcs which can
occur during style recalc.

The layout invalidations are pretty much only useful with devtools which keeps
handles to nodes for us. On the javascript side we can group the invalidations
however, but your point is a good one about having too many causes for any given
layout. I've switched the implementation in setNeedsLayout() to only record an
invalidation if it is the first call to setNeedsLayout. A web developer trying
to remove layouts of a given node may need to make several passes until all
causes are removed.

             setShouldDoFullPaintInvalidation();
         }
 
         // FIXME: This should just call deleteLineBoxTree, but that causes
         // crashes for fast/repaint tests.
         curr = firstRootBox();
         while (curr) {
             // Note: This uses nextRootBox() insted of nextLineBox() like deleteLineBoxTree does.
             RootInlineBox* next = curr->nextRootBox();
             curr->deleteLine();
@@ skipping 343 matching lines @@
     float logicalLeft = logicalLeftOffsetForLine(logicalHeight(), false).toFloat();
     float availableLogicalWidth = logicalRightOffsetForLine(logicalHeight(), false) - logicalLeft;
     updateLogicalWidthForAlignment(textAlign, 0, 0, logicalLeft, totalLogicalWidth, availableLogicalWidth, 0);
 
     if (!style()->isLeftToRightDirection())
         return logicalWidth() - logicalLeft;
     return logicalLeft;
 }
 
 }