Remove ElementFlags system.

sky/engine/core/dom/Element.h

Index: sky/engine/core/dom/Element.h
diff --git a/sky/engine/core/dom/Element.h b/sky/engine/core/dom/Element.h
index 339af0e5bf26fd6354e10ffeded8f4247703ded7..ab29ebc6b79fd612121a12274d439132ecda77fd 100644
--- a/sky/engine/core/dom/Element.h
+++ b/sky/engine/core/dom/Element.h
@@ -63,12 +63,6 @@ enum SpellcheckAttributeState {
     SpellcheckAttributeDefault
 };
 
-enum ElementFlags {
-    TabIndexWasSetExplicitly = 1 << 0,
-
-    NumberOfElementFlags = 2, // Required size of bitfield used to store the flags.
-};
-
 class Element : public ContainerNode {
     DEFINE_WRAPPERTYPEINFO();
 public:
@@ -298,8 +292,6 @@ protected:
     virtual void removedFrom(ContainerNode*) override;
     virtual void childrenChanged(const ChildrenChange&) override;
 
-    void clearTabIndexExplicitlyIfNeeded();
-    void setTabIndexExplicitly(short);
     // Subclasses may override this method to affect focusability. Unlike
     // supportsFocus, this method must be called on an up-to-date layout, so it
     // may use the renderer to reason about focusability. This method cannot be
@@ -317,11 +309,6 @@ private:
 
     bool classChangeNeedsStyleRecalc(const SpaceSplitString& oldClasses, const SpaceSplitString& newClasses);
 
-    bool hasElementFlag(ElementFlags mask) const { return hasRareData() && hasElementFlagInternal(mask); }
-    void setElementFlag(ElementFlags, bool value = true);
-    void clearElementFlag(ElementFlags);
-    bool hasElementFlagInternal(ElementFlags) const;
-
     bool isElementNode() const = delete; // This will catch anyone doing an unnecessary check.
     bool isDocumentFragment() const = delete; // This will catch anyone doing an unnecessary check.
     bool isDocumentNode() const = delete; // This will catch anyone doing an unnecessary check.