Devtools [LayoutEditor]: show selector info and highlight affected nodes

Source/core/inspector/InspectorOverlayHost.h

Index: Source/core/inspector/InspectorOverlayHost.h
diff --git a/Source/core/inspector/InspectorOverlayHost.h b/Source/core/inspector/InspectorOverlayHost.h
index b2a837964e2cf857ab5b74bf32c25a2d858b28b5..425db8cd38255c85eb33e617a95e0b81b5215998 100644
--- a/Source/core/inspector/InspectorOverlayHost.h
+++ b/Source/core/inspector/InspectorOverlayHost.h
@@ -52,6 +52,9 @@ public:
     void changeProperty(float delta);
     void endPropertyChange();
     void clearSelection(bool commitChanges);
+    void nextSelector();
+    void previousSelector();
+    String currentSelectorInfo();
 
     class Listener : public WillBeGarbageCollectedMixin {
     public:
@@ -62,6 +65,9 @@ public:
         virtual void overlayPropertyChanged(float cssDelta) = 0;
         virtual void overlayEndedPropertyChange() = 0;
         virtual void overlayClearSelection(bool commitChanges) = 0;
+        virtual void overlayNextSelector() = 0;
+        virtual void overlayPreviousSelector() = 0;
+        virtual String overlayCurrentSelectorInfo() = 0;
     };
     void setListener(Listener* listener) { m_listener = listener; }