Turn StyleSharing to 11.

sky/engine/core/css/resolver/SharedStyleFinder.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 84 matching lines @@
 
     if (!elementShadow && !candidateShadow)
         return true;
 
     if (static_cast<bool>(elementShadow) != static_cast<bool>(candidateShadow))
         return false;
 
     return elementShadow->hasSameStyles(candidateShadow);
 }
 
-bool SharedStyleFinder::sharingCandidateDistributedToSameInsertionPoint(Element& candidate) const
-{
-    Vector<RawPtr<InsertionPoint>, 8> insertionPoints, candidateInsertionPoints;
-    collectDestinationInsertionPoints(element(), insertionPoints);
-    collectDestinationInsertionPoints(candidate, candidateInsertionPoints);
-    if (insertionPoints.size() != candidateInsertionPoints.size())
-        return false;
-    for (size_t i = 0; i < insertionPoints.size(); ++i) {
-        if (insertionPoints[i] != candidateInsertionPoints[i])
-            return false;
-    }
-    return true;
-}
-
 bool SharedStyleFinder::canShareStyleWithElement(Element& candidate) const
 {
+    ASSERT(candidate.supportsStyleSharing());
+
     if (element() == candidate)
         return false;
-    Element* parent = candidate.parentOrShadowHostElement();
+    if (candidate.tagQName() != element().tagQName())
+        return false;
+    if (candidate.needsStyleRecalc())
+        return false;
     RenderStyle* style = candidate.renderStyle();
     if (!style)
         return false;
     if (!style->isSharable())
         return false;
+    ContainerNode* parent = NodeRenderingTraversal::parent(&candidate);
     if (!parent)
         return false;
-    if (element().parentOrShadowHostElement()->renderStyle() != parent->renderStyle())
+    RenderStyle* parentStyle = parent->renderStyle();
+    if (!parentStyle)
         return false;
-    if (candidate.tagQName() != element().tagQName())
-        return false;
-    if (candidate.inlineStyle())

[ojan, 2014/12/11 19:35:54]

Why don't we need this check? Where do we check that the inline styles are the
same? Can you explain in the change description why we don't need this check?

[esprehn, 2014/12/11 23:09:58]

supportsStyleSharing() contains this check, and we check that before adding
candidates. That's why I added the ASSERT() at the top of the function too.

-        return false;
-    if (candidate.needsStyleRecalc())
+    if (m_renderingParent->renderStyle()->inheritedNotEqual(parentStyle))
         return false;
     if (!sharingCandidateHasIdenticalStyleAffectingAttributes(candidate))
         return false;
-    if (candidate.hasID() && m_features.hasSelectorForId(candidate.idForStyleResolution()))

[ojan, 2014/12/11 19:35:54]

Getting rid of this means we do less work on pages with few IDs on things and
more work on pages where everything has IDs. I agree that removing this is
probably the right tradeoff. I wonder why this was even added in the first
place.

[esprehn, 2014/12/11 23:09:59]

This is also inside supportsStyleSharing().

-        return false;
     if (!sharingCandidateCanShareHostStyles(candidate))
         return false;
-    if (!sharingCandidateDistributedToSameInsertionPoint(candidate))
+    if (!candidate.treeScope().hasSameStyles(element().treeScope()))
         return false;
     if (candidate.isUnresolvedCustomElement() != element().isUnresolvedCustomElement())
         return false;
-
-    if (element().parentOrShadowHostElement() != parent) {
-        if (!parent->isStyledElement())
-            return false;
-        if (parent->inlineStyle())
-            return false;
-        if (parent->hasID() && m_features.hasSelectorForId(parent->idForStyleResolution()))
-            return false;
-    }
-
     return true;
 }
 
 bool SharedStyleFinder::documentContainsValidCandidate() const
 {
     for (Element* element = document().documentElement(); element; element = ElementTraversal::next(*element)) {
         if (element->supportsStyleSharing() && canShareStyleWithElement(*element))
             return true;
     }
     return false;
@@ skipping 24 matching lines @@
     if (!element().supportsStyleSharing())
         return 0;
 
     if (attributesAffectedByRules(element())) {
         INCREMENT_STYLE_STATS_COUNTER(m_styleResolver, sharedStyleRejectedByAttributeRules);
         return 0;
     }
 
     // Cache whether context.element() is affected by any known class selectors.
     m_elementAffectedByClassRules = element().hasClass() && classNamesAffectedByRules(element());
+    m_renderingParent = NodeRenderingTraversal::parent(&element());
 
     Element* shareElement = findElementForStyleSharing();
 
     if (!shareElement) {
         if (m_styleResolver.stats() && m_styleResolver.stats()->printMissedCandidateCount && documentContainsValidCandidate())
             INCREMENT_STYLE_STATS_COUNTER(m_styleResolver, sharedStyleMissed);
         return 0;
     }
 
     INCREMENT_STYLE_STATS_COUNTER(m_styleResolver, sharedStyleFound);
 
     if (attributesAffectedByRules(*shareElement)) {
         INCREMENT_STYLE_STATS_COUNTER(m_styleResolver, sharedStyleRejectedByAttributeRules);
         return 0;
     }
 
     return shareElement->renderStyle();
 }
 
 }