Correct box shadow overflow computation for InlineFlowBox

Source/core/layout/line/InlineFlowBox.cpp

 /*
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 726 matching lines @@
 
         if (curr->isInlineFlowBox())
             toInlineFlowBox(curr)->flipLinesInBlockDirection(lineTop, lineBottom);
         else
             curr->setLogicalTop(lineBottom - (curr->logicalTop() - lineTop) - curr->logicalHeight());
     }
 }
 
 inline void InlineFlowBox::addBoxShadowVisualOverflow(LayoutRect& logicalVisualOverflow)
 {
-    // box-shadow on root line boxes is applying to the block and not to the lines.
-    if (!parent())
+    const ComputedStyle& style = layoutObject().styleRef(isFirstLineStyle());
+
+    // box-shadow on the block element applies to the block and not to the lines,
+    // unless it is modified by :first-line pseudo element.
+    if (!parent() && (!isFirstLineStyle() || &style == layoutObject().style()))

[fs, 2015/06/18 08:47:33]

This is also true for border-image outsets and outline (below), so seems
reasonable to extend those predicates in the same way.

         return;
 
-    const ComputedStyle& style = layoutObject().styleRef(isFirstLineStyle());
     WritingMode writingMode = style.writingMode();
     ShadowList* boxShadow = style.boxShadow();
     if (!boxShadow)
         return;
 
     LayoutRectOutsets outsets(boxShadow->rectOutsetsIncludingOriginal());
     // Similar to how glyph overflow works, if our lines are flipped, then it's actually the opposite shadow that applies, since
     // the line is "upside down" in terms of block coordinates.
     LayoutRectOutsets logicalOutsets(outsets.logicalOutsetsWithFlippedLines(writingMode));
 
@@ skipping 549 matching lines @@
         ASSERT(child->prevOnLine() == prev);
         prev = child;
     }
     ASSERT(prev == m_lastChild);
 #endif
 }
 
 #endif
 
 } // namespace blink