Avoid unnecessary invalidation scheduling.

third_party/WebKit/Source/core/dom/StyleEngine.cpp

Index: third_party/WebKit/Source/core/dom/StyleEngine.cpp
diff --git a/third_party/WebKit/Source/core/dom/StyleEngine.cpp b/third_party/WebKit/Source/core/dom/StyleEngine.cpp
index d5d9941d1cae10ee2b6c1a26c426a48a399dd7cf..683aca29c91411eb173412007f394e40b8db5621 100644
--- a/third_party/WebKit/Source/core/dom/StyleEngine.cpp
+++ b/third_party/WebKit/Source/core/dom/StyleEngine.cpp
@@ -627,9 +627,23 @@ void StyleEngine::platformColorsChanged()
     document().setNeedsStyleRecalc(SubtreeStyleChange, StyleChangeReasonForTracing::create(StyleChangeReason::PlatformColorChange));
 }
 
+bool StyleEngine::shouldSkipInvalidationFor(const Element& element) const
+{
+    if (!isMaster())
+        return true;

[rune, 2015/12/10 08:08:52]

Should I rely on non-master documents having a null-resolver and
ASSERT(isMaster()) below the resolver() check instead of this if-check?

[esprehn, 2015/12/10 08:53:47]

the non master will also not be active, so it'll fail the inActiveDocument()

+    if (!resolver())
+        return true;
+    if (!element.inActiveDocument())
+        return true;
+    if (!element.parentNode())
+        return true;
+    return element.parentNode()->styleChangeType() >= SubtreeStyleChange;
+}
+
 void StyleEngine::classChangedForElement(const SpaceSplitString& changedClasses, Element& element)
 {
-    ASSERT(isMaster());
+    if (shouldSkipInvalidationFor(element))

[esprehn, 2015/12/10 08:53:47]

classChangedForElement is guarded by:

    bool testShouldInvalidateStyle = inActiveDocument() && styleResolver;


idAttribute and others are guarded the same since accessing the styleEngine()
will crash if you're not in an active document.

I don't think you need either of those checks in the skip method, it should
perhaps just assert?

[esprehn, 2015/12/10 08:57:01]

Oh I see you removed all those checks, this seems fine then.

+        return;
     InvalidationLists invalidationLists;
     unsigned changedSize = changedClasses.size();
     RuleFeatureSet& ruleFeatureSet = ensureResolver().ensureUpdatedRuleFeatureSet();
@@ -640,7 +654,9 @@ void StyleEngine::classChangedForElement(const SpaceSplitString& changedClasses,
 
 void StyleEngine::classChangedForElement(const SpaceSplitString& oldClasses, const SpaceSplitString& newClasses, Element& element)
 {
-    ASSERT(isMaster());
+    if (shouldSkipInvalidationFor(element))
+        return;
+
     if (!oldClasses.size()) {
         classChangedForElement(newClasses, element);
         return;
@@ -681,7 +697,9 @@ void StyleEngine::classChangedForElement(const SpaceSplitString& oldClasses, con
 
 void StyleEngine::attributeChangedForElement(const QualifiedName& attributeName, Element& element)
 {
-    ASSERT(isMaster());
+    if (shouldSkipInvalidationFor(element))
+        return;
+
     InvalidationLists invalidationLists;
     ensureResolver().ensureUpdatedRuleFeatureSet().collectInvalidationSetsForAttribute(invalidationLists, element, attributeName);
     m_styleInvalidator.scheduleInvalidationSetsForElement(invalidationLists, element);
@@ -689,7 +707,9 @@ void StyleEngine::attributeChangedForElement(const QualifiedName& attributeName,
 
 void StyleEngine::idChangedForElement(const AtomicString& oldId, const AtomicString& newId, Element& element)
 {
-    ASSERT(isMaster());
+    if (shouldSkipInvalidationFor(element))
+        return;
+
     InvalidationLists invalidationLists;
     RuleFeatureSet& ruleFeatureSet = ensureResolver().ensureUpdatedRuleFeatureSet();
     if (!oldId.isEmpty())
@@ -701,7 +721,9 @@ void StyleEngine::idChangedForElement(const AtomicString& oldId, const AtomicStr
 
 void StyleEngine::pseudoStateChangedForElement(CSSSelector::PseudoType pseudoType, Element& element)
 {
-    ASSERT(isMaster());
+    if (shouldSkipInvalidationFor(element))
+        return;
+
     InvalidationLists invalidationLists;
     ensureResolver().ensureUpdatedRuleFeatureSet().collectInvalidationSetsForPseudoClass(invalidationLists, element, pseudoType);
     m_styleInvalidator.scheduleInvalidationSetsForElement(invalidationLists, element);