[selectors4] Implement :focus-within pseudo-class

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

Index: third_party/WebKit/Source/core/dom/ContainerNode.h
diff --git a/third_party/WebKit/Source/core/dom/ContainerNode.h b/third_party/WebKit/Source/core/dom/ContainerNode.h
index 872f040edbb3a12ed2e365d624cef76ee68cf1f5..7135f6e61fda2f3f47ddd673b465cdfc0c14b7b4 100644
--- a/third_party/WebKit/Source/core/dom/ContainerNode.h
+++ b/third_party/WebKit/Source/core/dom/ContainerNode.h
@@ -57,8 +57,9 @@ enum DynamicRestyleFlags {
   kChildrenAffectedByBackwardPositionalRules = 1 << 9,
   kAffectedByFirstChildRules = 1 << 10,
   kAffectedByLastChildRules = 1 << 11,
+  kChildrenOrSiblingsAffectedByFocusWithin = 1 << 12,
 
-  kNumberOfDynamicRestyleFlags = 12,
+  kNumberOfDynamicRestyleFlags = 13,
 
   kChildrenAffectedByStructuralRules =
       kChildrenAffectedByFirstChildRules | kChildrenAffectedByLastChildRules |
@@ -139,6 +140,7 @@ class CORE_EXPORT ContainerNode : public Node {
   LayoutRect BoundingBox() const final;
   void SetFocused(bool, WebFocusType) override;
   void FocusStateChanged();
+  void FocusWithinStateChanged();
   void SetActive(bool = true) override;
   void SetDragged(bool) override;
   void SetHovered(bool = true) override;
@@ -150,6 +152,13 @@ class CORE_EXPORT ContainerNode : public Node {
     SetRestyleFlag(kChildrenOrSiblingsAffectedByFocus);
   }
 
+  bool ChildrenOrSiblingsAffectedByFocusWithin() const {
+    return HasRestyleFlag(kChildrenOrSiblingsAffectedByFocusWithin);
+  }
+  void SetChildrenOrSiblingsAffectedByFocusWithin() {
+    SetRestyleFlag(kChildrenOrSiblingsAffectedByFocusWithin);
+  }
+
   bool ChildrenOrSiblingsAffectedByHover() const {
     return HasRestyleFlag(kChildrenOrSiblingsAffectedByHover);
   }