Implement style invalidation tree walk for targeted style recalc upon class change.

Source/core/dom/Node.cpp

Index: Source/core/dom/Node.cpp
diff --git a/Source/core/dom/Node.cpp b/Source/core/dom/Node.cpp
index 66bbfbc6ed3a15a48c01fb584c3860fdf2c6ef0b..9f00cf0c0126e27db54d863846b57441ce361ba8 100644
--- a/Source/core/dom/Node.cpp
+++ b/Source/core/dom/Node.cpp
@@ -639,6 +639,14 @@ void Node::setIsLink(bool isLink)
     setFlag(isLink && !SVGImage::isInSVGImage(toElement(this)), IsLinkFlag);
 }
 
+void Node::markAncestorsWithChildNeedsStyleInvalidation()
+{
+    for (Node* node = this; node && !node->childNeedsDistributionRecalc(); node = node->parentOrShadowHostNode())
+        node->setChildNeedsStyleInvalidation();
+    if (document().childNeedsStyleInvalidation())
+        document().scheduleStyleRecalc();
+}
+
 void Node::markAncestorsWithChildNeedsDistributionRecalc()
 {
     for (Node* node = this; node && !node->childNeedsDistributionRecalc(); node = node->parentOrShadowHostNode())