overview: Don't display minimized windows differently in the overview

Making them not fully opaque just makes them harder to see and there is no reason why the user should care whether the window is minimized or not when
switching to a window display them like any other windows.

https://bugzilla.gnome.org/show_bug.cgi?id=693991

js/ui/workspace.js

@@ -1211,9 +1211,8 @@ const Workspace = new Lang.Class({
                         clone.actor.y = y;
                     }
 
-                    // Make the window slightly transparent to indicate it's hidden
                     Tweener.addTween(clone.actor,
-                                     { opacity: 128,
+                                     { opacity: 255,
                                        time: Overview.ANIMATION_TIME,
                                        transition: 'easeInQuad'
                                      });