Gui: Remove unnecessary 'started' variable member in navigation animation

src/Gui/NavigationAnimation.cpp

@@ -28,18 +28,17 @@
 using namespace Gui;
 
 NavigationAnimation::NavigationAnimation(NavigationStyle* navigation)
-    : navigation(navigation), started(false)
+    : navigation(navigation)
 {}
 
 void NavigationAnimation::startAnimation(QAbstractAnimation::DeletionPolicy policy)
 {
-    started = true;
     QAbstractAnimation::start(policy);
 }
 
 void NavigationAnimation::updateCurrentValue(const QVariant& value)
 {
-    if (!started) {
+    if (state() == QAbstractAnimation::State::Stopped) {
         return;
     }
     update(value);

src/Gui/NavigationAnimation.h

@@ -45,8 +45,6 @@ protected:
     virtual void stopAnimation();
 
 private:
-    bool started;
-
     void startAnimation(QAbstractAnimation::DeletionPolicy policy = KeepWhenStopped);
     void updateCurrentValue(const QVariant& value) override;
 

src/Gui/NavigationAnimator.cpp

@@ -94,7 +94,6 @@ void NavigationAnimator::stop()
  */
 void NavigationAnimator::reset() {
     disconnect(activeAnimation.get(), &NavigationAnimation::finished, 0, 0);
-    activeAnimation->started = false;
     activeAnimation->stopAnimation();
     activeAnimation.reset();
 }