[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 e91ca9b92d2f0dc9307dec909434be606825eb9c..dfc7fc7364ca1ce237a811e7dd715f064b29f6b9 100644
--- a/third_party/WebKit/Source/core/dom/ContainerNode.h
+++ b/third_party/WebKit/Source/core/dom/ContainerNode.h
@@ -56,8 +56,9 @@ enum DynamicRestyleFlags {
   kChildrenAffectedByBackwardPositionalRules = 1 << 9,
   kAffectedByFirstChildRules = 1 << 10,
   kAffectedByLastChildRules = 1 << 11,
+  kChildrenOrSiblingsAffectedByFocusWithin = 1 << 12,
 
-  kNumberOfDynamicRestyleFlags = 12,
+  kNumberOfDynamicRestyleFlags = 13,
 
   kChildrenAffectedByStructuralRules =
       kChildrenAffectedByFirstChildRules | kChildrenAffectedByLastChildRules |
@@ -138,6 +139,7 @@ class CORE_EXPORT ContainerNode : public Node {
   LayoutRect BoundingBox() const final;
   void SetFocused(bool) override;
   void FocusStateChanged();
+  void FocusWithinStateChanged();
   void SetActive(bool = true) override;
   void SetDragged(bool) override;
   void SetHovered(bool = true) override;
@@ -149,6 +151,13 @@ class CORE_EXPORT ContainerNode : public Node {
     SetRestyleFlag(kChildrenOrSiblingsAffectedByFocus);
   }
 
+  bool ChildrenOrSiblingsAffectedByFocusWithin() const {
+    return HasRestyleFlag(kChildrenOrSiblingsAffectedByFocusWithin);
+  }
+  void SetChildrenOrSiblingsAffectedByFocusWithin() {
+    SetRestyleFlag(kChildrenOrSiblingsAffectedByFocusWithin);
+  }
+
   bool ChildrenOrSiblingsAffectedByHover() const {
     return HasRestyleFlag(kChildrenOrSiblingsAffectedByHover);
   }