Navigation transitions (web to native app): Hide/Show transition elements (Blink side)

Source/core/dom/Document.h

Index: Source/core/dom/Document.h
diff --git a/Source/core/dom/Document.h b/Source/core/dom/Document.h
index 76a457c6f7aa9250e91b1b12129fcd5562990657..1d49b225d492a6c05dc0e851c558e68a0c34867a 100644
--- a/Source/core/dom/Document.h
+++ b/Source/core/dom/Document.h
@@ -386,6 +386,7 @@ public:
     bool isTransitionDocument() const { return m_isTransitionDocument; }
     void setIsTransitionDocument() { m_isTransitionDocument = true; }
     void hideTransitionElements(const AtomicString& cssSelector);
+    void showTransitionElements(const AtomicString& cssSelector);
 
     struct TransitionElement {
         String id;
@@ -1167,6 +1168,8 @@ private:
     using EventFactorySet = HashSet<OwnPtr<EventFactoryBase>>;
     static EventFactorySet& eventFactories();
 
+    void updateElementOpacity(const AtomicString& cssSelector, double opacity);
+
     DocumentLifecycle m_lifecycle;
 
     bool m_hasNodesWithPlaceholderStyle;