[escher/app] Remove poor man's RTTI

escher/include/escher/app.h

@@ -45,7 +45,6 @@ public:
   /* The destructor has to be virtual. Otherwise calling a destructor on an
    * App * pointing to a Derived App would have undefined behaviour. */
   virtual ~App() = default;
-  constexpr static uint8_t Magic = 0xA8;
   Snapshot * snapshot();
   void setFirstResponder(Responder * responder);
   Responder * firstResponder();
@@ -57,7 +56,6 @@ public:
     KDCoordinate topMargin = 0, KDCoordinate leftMargin = 0, KDCoordinate bottomMargin = 0, KDCoordinate rightMargin = 0);
   void dismissModalViewController();
   void displayWarning(I18n::Message warningMessage1, I18n::Message warningMessage2 = (I18n::Message) 0, bool specialExitKeys = false);
-  uint8_t m_magic; // Poor man's RTTI
 
   virtual void didBecomeActive(Window * window);
   virtual void willBecomeInactive();

escher/src/app.cpp

@@ -31,7 +31,6 @@ void App::Snapshot::tidy() {
 
 App::App(Snapshot * snapshot, ViewController * rootViewController, I18n::Message warningMessage) :
   Responder(nullptr),
-  m_magic(Magic),
   m_modalViewController(this, rootViewController),
   m_firstResponder(nullptr),
   m_snapshot(snapshot),

escher/src/responder.cpp

@@ -69,10 +69,6 @@ App * Responder::app() const {
   while (rootResponder->parentResponder() != nullptr) {
     rootResponder = rootResponder->parentResponder();
   }
-  /* If we used RTTI we could use a dynamic_cast, which would be a lot more
-   * safe, as such:
-   * return dynamic_cast<App *>(rootResponder); */
    App * result = (App *)rootResponder;
-   assert(result->m_magic == App::Magic); // Poor man's RTTI
   return result;
 }