DevTools: make InspectorDebuggerAgent aggregate V8DebuggerAgent instead of inheriting

Source/core/inspector/InspectorBaseAgent.h

Index: Source/core/inspector/InspectorBaseAgent.h
diff --git a/Source/core/inspector/InspectorBaseAgent.h b/Source/core/inspector/InspectorBaseAgent.h
index 077f957ab849f8638c326ab64a5bdae04d67161a..c3411e75c2891740ccb6230ff0a53c57e88ff3ce 100644
--- a/Source/core/inspector/InspectorBaseAgent.h
+++ b/Source/core/inspector/InspectorBaseAgent.h
@@ -102,13 +102,13 @@ class InspectorBaseAgent : public InspectorAgent {
 public:
     ~InspectorBaseAgent() override { }
 
-    void setFrontend(InspectorFrontend* frontend) final
+    void setFrontend(InspectorFrontend* frontend) override
     {
         ASSERT(!m_frontend);
         m_frontend = FrontendClass::from(frontend);
     }
 
-    void clearFrontend() final
+    void clearFrontend() override
     {
         ErrorString error;
         disable(&error);