Delete AuthorStyleInfo and move its data into ComputedStyle.RareNonInheritedData.

Source/core/css/resolver/StyleResolver.cpp

Index: Source/core/css/resolver/StyleResolver.cpp
diff --git a/Source/core/css/resolver/StyleResolver.cpp b/Source/core/css/resolver/StyleResolver.cpp
index 75a480c3d6d890defa7fb5bd4d0483c22440185c..5684d6e9762706eed2528a6c3177256cb12639bd 100644
--- a/Source/core/css/resolver/StyleResolver.cpp
+++ b/Source/core/css/resolver/StyleResolver.cpp
@@ -530,32 +530,10 @@ PassRefPtr<ComputedStyle> StyleResolver::styleForDocument(Document& document)
     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.
@@ -1415,6 +1393,17 @@ void StyleResolver::applyMatchedProperties(StyleResolverState& state, const Matc
         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())) {
@@ -1425,6 +1414,29 @@ void StyleResolver::applyMatchedProperties(StyleResolverState& state, const Matc
     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)