Update PseudoElements during recalcStyle.

third_party/WebKit/Source/core/style/ComputedStyle.cpp

 /*
  * Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2011 Adobe Systems Incorporated. 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 150 matching lines @@
     , m_rareInheritedData(o.m_rareInheritedData)
     , m_styleInheritedData(o.m_styleInheritedData)
     , m_svgStyle(o.m_svgStyle)
     , m_inheritedData(o.m_inheritedData)
     , m_nonInheritedData(o.m_nonInheritedData)
 {
 }
 
 static StyleRecalcChange diffPseudoStyles(const ComputedStyle& oldStyle, const ComputedStyle& newStyle)
 {
-    // If the pseudoStyles have changed, we want any StyleRecalcChange that is not NoChange
-    // because setStyle will do the right thing with anything else.
-    if (!oldStyle.hasAnyPublicPseudoStyles())

[skobes, 2016/09/24 00:11:39]

We should avoid looping in the common case that neither oldStyle nor newStyle
has pseudo styles.  Can we just update the condition here to be:

if (!oldStyle.hasAnyPublicPseudoStyles() &&
!newStyle.hasAnyPublicPseudoStyles())

-        return NoChange;
+    if (!oldStyle.hasAnyPublicPseudoStyles()) {
+        // If newStyle has PseudoStyle UpdatePseudoElements will ensure layoutObject to setStyle.
+        for (PseudoId pseudoId = FirstPublicPseudoId; pseudoId < FirstInternalPseudoId; pseudoId = static_cast<PseudoId>(pseudoId + 1)) {

[skobes, 2016/09/24 00:11:39]

Instead of adding another loop let's update the main loop below to only skip if
neither oldStyle nor newStyle has the pseudo style for that id.

+            if (oldStyle.hasPseudoStyle(pseudoId) != newStyle.hasPseudoStyle(pseudoId))
+                return UpdatePseudoElements;
+        }
+    }
+
     for (PseudoId pseudoId = FirstPublicPseudoId; pseudoId < FirstInternalPseudoId; pseudoId = static_cast<PseudoId>(pseudoId + 1)) {
         if (!oldStyle.hasPseudoStyle(pseudoId))
             continue;
         const ComputedStyle* newPseudoStyle = newStyle.getCachedPseudoStyle(pseudoId);
         if (!newPseudoStyle)
             return NoInherit;
         const ComputedStyle* oldPseudoStyle = oldStyle.getCachedPseudoStyle(pseudoId);
         if (oldPseudoStyle && *oldPseudoStyle != *newPseudoStyle)
             return NoInherit;
     }
@@ skipping 1857 matching lines @@
         if (value < 0)
             fvalue -= 0.5f;
         else
             fvalue += 0.5f;
     }
 
     return roundForImpreciseConversion<int>(fvalue / zoomFactor);
 }
 
 } // namespace blink