CSS: Avoid invalidating style when only descendants need updating

Source/core/css/invalidation/StyleInvalidator.cpp

 
 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 
 #include "core/css/invalidation/StyleInvalidator.h"
 
 #include "core/css/invalidation/InvalidationSet.h"
@@ skipping 32 matching lines @@
 void StyleInvalidator::scheduleInvalidation(PassRefPtrWillBeRawPtr<InvalidationSet> invalidationSet, Element& element)
 {
     ASSERT(element.inActiveDocument());
     if (element.styleChangeType() >= SubtreeStyleChange)
         return;
     if (invalidationSet->wholeSubtreeInvalid()) {
         element.setNeedsStyleRecalc(SubtreeStyleChange, StyleChangeReasonForTracing::create(StyleChangeReason::StyleInvalidator));
         clearInvalidation(element);
         return;
     }
-    if (invalidationSet->isEmpty()) {
+    if (invalidationSet->invalidatesSelf())
         element.setNeedsStyleRecalc(LocalStyleChange, StyleChangeReasonForTracing::create(StyleChangeReason::StyleInvalidator));
+
+    if (invalidationSet->isEmpty())
         return;
-    }
 
     InvalidationList& list = ensurePendingInvalidationList(element);
     list.append(invalidationSet);
     element.setNeedsStyleInvalidation();
 }
 
 StyleInvalidator::InvalidationList& StyleInvalidator::ensurePendingInvalidationList(Element& element)
 {
     PendingInvalidationMap::AddResult addResult = m_pendingInvalidationMap.add(&element, nullptr);
     if (addResult.isNewEntry)
@@ skipping 54 matching lines @@
 
     return false;
 }
 
 ALWAYS_INLINE bool StyleInvalidator::checkInvalidationSetsAgainstElement(Element& element, StyleInvalidator::RecursionData& recursionData)
 {
     if (element.styleChangeType() >= SubtreeStyleChange || recursionData.wholeSubtreeInvalid()) {
         recursionData.setWholeSubtreeInvalid();
         return false;
     }
+    bool thisElementNeedsStyleRecalc = recursionData.matchesCurrentInvalidationSets(element);
     if (element.needsStyleInvalidation()) {
         if (InvalidationList* invalidationList = m_pendingInvalidationMap.get(&element)) {
             for (const auto& invalidationSet : *invalidationList)
                 recursionData.pushInvalidationSet(*invalidationSet);
             if (UNLIKELY(*s_tracingEnabled)) {
                 TRACE_EVENT_INSTANT1(TRACE_DISABLED_BY_DEFAULT("devtools.timeline.invalidationTracking"),
                     "StyleInvalidatorInvalidationTracking",
                     TRACE_EVENT_SCOPE_THREAD,
                     "data", InspectorStyleInvalidatorInvalidateEvent::invalidationList(element, *invalidationList));
             }
-            return true;
         }
     }
-
-    return recursionData.matchesCurrentInvalidationSets(element);
+    return thisElementNeedsStyleRecalc;
 }
 
 bool StyleInvalidator::invalidateChildren(Element& element, StyleInvalidator::RecursionData& recursionData)
 {
     bool someChildrenNeedStyleRecalc = false;
     for (ShadowRoot* root = element.youngestShadowRoot(); root; root = root->olderShadowRoot()) {
         if (!recursionData.treeBoundaryCrossing() && !root->childNeedsStyleInvalidation() && !root->needsStyleInvalidation())
             continue;
         for (Element* child = ElementTraversal::firstChild(*root); child; child = ElementTraversal::nextSibling(*child)) {
             bool childRecalced = invalidate(*child, recursionData);
@@ skipping 42 matching lines @@
 }
 
 DEFINE_TRACE(StyleInvalidator)
 {
 #if ENABLE(OILPAN)
     visitor->trace(m_pendingInvalidationMap);
 #endif
 }
 
 } // namespace blink