Fix FAB behavior

app/src/main/java/eu/kanade/tachiyomi/widget/FABAnimationBase.kt

@@ -5,7 +5,7 @@ import android.support.design.widget.FloatingActionButton
 import android.support.v4.view.ViewCompat
 import android.view.View
 
-abstract class FABAnimationBase() : FloatingActionButton.Behavior() {
+abstract class FABAnimationBase : FloatingActionButton.Behavior() {
 
     var isAnimatingOut = false
 

app/src/main/java/eu/kanade/tachiyomi/widget/FABAnimationUpDown.kt

@@ -34,7 +34,7 @@ class FABAnimationUpDown @JvmOverloads constructor(ctx: Context, attrs: Attribut
 
             override fun onAnimationEnd(animation: Animation) {
                 isAnimatingOut = false
-                button.visibility = View.GONE
+                button.visibility = View.INVISIBLE
             }
 
             override fun onAnimationRepeat(animation: Animation) {