DevTools: disable DOMDebuggerAgent when DOMAgent or DebuggerAgent were disabled.

Source/core/inspector/InspectorDebuggerAgent.h

Index: Source/core/inspector/InspectorDebuggerAgent.h
diff --git a/Source/core/inspector/InspectorDebuggerAgent.h b/Source/core/inspector/InspectorDebuggerAgent.h
index 731f6bd156d6271d59a3d7f436755b1619ae6c39..02f2d6eac6d2ccfabc2a2966f6e042945a0ae73e 100644
--- a/Source/core/inspector/InspectorDebuggerAgent.h
+++ b/Source/core/inspector/InspectorDebuggerAgent.h
@@ -169,6 +169,8 @@ public:
     };
     void setListener(Listener* listener) { m_listener = listener; }
 
+    bool enabled();
+
     virtual ScriptDebugServer& scriptDebugServer() = 0;
 
     void setBreakpoint(const String& scriptId, int lineNumber, int columnNumber, BreakpointSource, const String& condition = String());
@@ -199,8 +201,6 @@ private:
     void cancelPauseOnNextStatement();
     void addMessageToConsole(MessageSource, MessageType);
 
-    bool enabled();
-
     PassRefPtr<TypeBuilder::Array<TypeBuilder::Debugger::CallFrame> > currentCallFrames();
     PassRefPtr<TypeBuilder::Debugger::StackTrace> currentAsyncStackTrace();