Invalidate first line display item clients when first line style changes

third_party/WebKit/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 2047 matching lines @@
     LayoutUnit totalLogicalWidth;
     LayoutUnit logicalLeft = logicalLeftOffsetForLine(logicalHeight(), false);
     LayoutUnit availableLogicalWidth = logicalRightOffsetForLine(logicalHeight(), false) - logicalLeft;
     updateLogicalWidthForAlignment(textAlign, 0, 0, logicalLeft, totalLogicalWidth, availableLogicalWidth, 0);
 
     if (!style()->isLeftToRightDirection())
         return logicalWidth() - logicalLeft;
     return logicalLeft;
 }
 
+void LayoutBlockFlow::invalidateDisplayItemClientsOfFirstLine()
+{
+    if (RootInlineBox* firstRootBox = this->firstRootBox())
+        firstRootBox->invalidateDisplayItemClientsOfFirstLine();
+    else if (firstChild()->isLayoutBlockFlow())

[chrishtr, 2015/12/01 01:43:11]

Add a comment explaining each side of the if ... else branch.

[mstensho (USE GERRIT), 2015/12/01 12:29:49]

How do we know that we have children at all? Also, this will enter any first
block flow child, including floats and out-of-flow positioned objects. That's
unnecessary, since they never apply ::fist-line rules from ancestors.

[Xianzhu, 2015/12/01 20:06:25]

Done.

[Xianzhu, 2015/12/01 20:06:25]

It seems that if the block has at least one non-inline child, it will be
!childrenInline(), otherwise it always has a root line box, so
   ASSERT(!firstRootBox() || firstChild())
However the above rule looks not explicit and I changed code to make it clearer.
Fixed.

+        toLayoutBlockFlow(firstChild())->invalidateDisplayItemClientsOfFirstLine();
 }
+
+}