Delete AuthorStyleInfo and move its data into ComputedStyle.RareNonInheritedData.

Source/core/css/resolver/StyleResolver.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 512 matching lines @@
     // so that the common case doesn't need to create a new ComputedStyle in
     // Document::inheritHtmlAndBodyElementStyles.
     documentStyle->setDisplay(BLOCK);
     documentStyle->setPosition(AbsolutePosition);
 
     document.setupFontBuilder(*documentStyle);
 
     return documentStyle.release();
 }
 
-AuthorStyleInfo StyleResolver::authorStyleInfo(StyleResolverState& state)
-{
-    const CachedUAStyle* cachedUAStyle = state.cachedUAStyle();
-
-    if (!cachedUAStyle)
-        return AuthorStyleInfo();
-
-    // Exclude background-repeat from comparison by resetting it.
-    FillLayer backgroundCopy = cachedUAStyle->backgroundLayers;
-    FillLayer backgroundLayersCopy = state.style()->backgroundLayers();
-    backgroundCopy.setRepeatX(NoRepeatFill);
-    backgroundCopy.setRepeatY(NoRepeatFill);
-    backgroundLayersCopy.setRepeatX(NoRepeatFill);
-    backgroundLayersCopy.setRepeatY(NoRepeatFill);
-
-    bool backgroundChanged = backgroundLayersCopy != backgroundCopy
-        || state.style()->backgroundColor() != cachedUAStyle->backgroundColor;
-    bool borderChanged = state.style()->border() != cachedUAStyle->border;
-
-    return AuthorStyleInfo(backgroundChanged, borderChanged);
-}
-
 void StyleResolver::adjustComputedStyle(StyleResolverState& state, Element* element)
 {
     StyleAdjuster adjuster(document().inQuirksMode());
-    adjuster.adjustComputedStyle(state.mutableStyleRef(), *state.parentStyle(), element, authorStyleInfo(state));
+    adjuster.adjustComputedStyle(state.mutableStyleRef(), *state.parentStyle(), element);
 }
 
 // Start loading resources referenced by this style.
 void StyleResolver::loadPendingResources(StyleResolverState& state)
 {
     m_styleResourceLoader.loadPendingResources(state.style(), state.elementStyleResources());
     document().styleEngine().fontSelector()->fontLoader()->loadPendingFonts();
 }
 
 PassRefPtr<ComputedStyle> StyleResolver::styleForElement(Element* element, const ComputedStyle* defaultParent, StyleSharingBehavior sharingBehavior,
@@ skipping 839 matching lines @@
 
     // Cache the UA properties to pass them to LayoutTheme in adjustComputedStyle.
     state.cacheUserAgentBorderAndBackground();
 
     // Now do the author and user normal priority properties and all the !important properties.
     applyMatchedProperties<LowPropertyPriority>(state, matchResult.authorRules(), false, applyInheritedOnly);
     for (auto range : ImportantAuthorRanges(matchResult))
         applyMatchedProperties<LowPropertyPriority>(state, range, true, applyInheritedOnly);
     applyMatchedProperties<LowPropertyPriority>(state, matchResult.uaRules(), true, applyInheritedOnly);
 
+    if (state.style()->hasAppearance() && !applyInheritedOnly) {
+        // Check whether the final border and background differs from the cached UA ones.
+        // When there is a partial match in the MatchedPropertiesCache, the non-inherited values are copied from

[Timothy Loh, 2015/08/25 08:08:20]

This comment took me a couple of reads to get, maybe just saying
// When there is a partial match in the MatchedPropertiesCache, these flags
// will already be set correctly and the computation here would be incorrect.
is enough? Since there's a test, it should be easy enough for someone to see
that the check is at least needed.

[meade_UTC10, 2015/08/25 08:22:51]

The comment about what happens in cacheUserAgentBorderAndBackground was the key
to understanding why this is the case for me. How about this?

+        // the cache, and cacheUserAgentBorderAndBackground caches those. In that case, hasAuthorBackground/Border
+        // compares the final style with itself and returns the wrong result, but
+        // state.style().hasAuthorBackground has already been calculated and cached, so it's ok not to do this
+        // check again.
+        state.style()->setHasAuthorBackground(hasAuthorBackground(state));
+        state.style()->setHasAuthorBorder(hasAuthorBorder(state));
+    }
+
     loadPendingResources(state);
 
     if (!cachedMatchedProperties && cacheHash && MatchedPropertiesCache::isCacheable(element, *state.style(), *state.parentStyle())) {
         INCREMENT_STYLE_STATS_COUNTER(*this, matchedPropertyCacheAdded, 1);
         m_matchedPropertiesCache.add(*state.style(), *state.parentStyle(), cacheHash, matchResult.matchedProperties());
     }
 
     ASSERT(!state.fontBuilder().fontDirty());
 }
 
+bool StyleResolver::hasAuthorBackground(const StyleResolverState& state)
+{
+    const CachedUAStyle* cachedUAStyle = state.cachedUAStyle();
+    if (!cachedUAStyle)
+        return false;
+
+    FillLayer oldFill = cachedUAStyle->backgroundLayers;
+    FillLayer newFill = state.style()->backgroundLayers();
+    // Exclude background-repeat from comparison by resetting it.
+    oldFill.setRepeatX(NoRepeatFill);
+    oldFill.setRepeatY(NoRepeatFill);
+    newFill.setRepeatX(NoRepeatFill);
+    newFill.setRepeatY(NoRepeatFill);
+
+    return (oldFill != newFill || cachedUAStyle->backgroundColor != state.style()->backgroundColor());
+}
+
+bool StyleResolver::hasAuthorBorder(const StyleResolverState& state)
+{
+    const CachedUAStyle* cachedUAStyle = state.cachedUAStyle();
+    return cachedUAStyle && (cachedUAStyle->border != state.style()->border());
+}
+
 void StyleResolver::applyCallbackSelectors(StyleResolverState& state)
 {
     if (!m_watchedSelectorsRules)
         return;
 
     ElementRuleCollector collector(state.elementContext(), m_selectorFilter, state.style());
     collector.setMode(SelectorChecker::CollectingStyleRules);
 
     MatchRequest matchRequest(m_watchedSelectorsRules.get(), true);
     collector.collectMatchingRules(matchRequest);
@@ skipping 70 matching lines @@
     visitor->trace(m_watchedSelectorsRules);
     visitor->trace(m_treeBoundaryCrossingScopes);
     visitor->trace(m_styleResourceLoader);
     visitor->trace(m_styleSharingLists);
     visitor->trace(m_pendingStyleSheets);
     visitor->trace(m_document);
 #endif
 }
 
 } // namespace blink