[selectors4] Use common ancestor strategy for :focus-within

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

Index: third_party/WebKit/Source/core/dom/ContainerNode.cpp
diff --git a/third_party/WebKit/Source/core/dom/ContainerNode.cpp b/third_party/WebKit/Source/core/dom/ContainerNode.cpp
index 3de58c2b8b065a3bc08c1e1f237b27374c12ecc8..5b66c1f31e9eccb69e19d331c67170047c010f59 100644
--- a/third_party/WebKit/Source/core/dom/ContainerNode.cpp
+++ b/third_party/WebKit/Source/core/dom/ContainerNode.cpp
@@ -1044,7 +1044,9 @@ void ContainerNode::FocusWithinStateChanged() {
     ToElement(this)->PseudoStateChanged(CSSSelector::kPseudoFocusWithin);
 }
 
-void ContainerNode::SetFocused(bool received, WebFocusType focus_type) {
+void ContainerNode::SetFocused(bool received,
+                               WebFocusType focus_type,
+                               Node* common_ancestor) {
   // Recurse up author shadow trees to mark shadow hosts if it matches :focus.
   // TODO(kochi): Handle UA shadows which marks multiple nodes as focused such
   // as <input type="date"> the same way as author shadow.
@@ -1070,7 +1072,7 @@ void ContainerNode::SetFocused(bool received, WebFocusType focus_type) {
   FocusStateChanged();
 
   UpdateDistribution();
-  for (ContainerNode* node = this; node;
+  for (ContainerNode* node = this; node && node != common_ancestor;
        node = FlatTreeTraversal::Parent(*node)) {
     node->SetHasFocusWithin(received);
     node->FocusWithinStateChanged();