Remove support for debugging JS with Qt 4.7

Remove infrastructure to debug/inspect QML applications with Qt 4.7.

Change-Id: I277e9884e009475a29017f502bbe1d069317460f
Reviewed-by: hjk <hjk121@nokiamail.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

src/plugins/qmlprojectmanager/qmlprojectplugin.h

@@ -47,8 +47,6 @@ public:
 
     virtual bool initialize(const QStringList &arguments, QString *errorString);
     virtual void extensionsInitialized();
-
-    static void showQmlObserverToolWarning();
 };
 
 } // namespace QmlProject