js: Use implicit animations for animatable properties

We now have everything in place to replace Tweener for all animatable
properties with implicit animations, which has the following benefits:

 - they run entirely in C, while Tweener requires context switches
   to JS each frame

 - they are more reliable, as Tweener only detects when an animation
   is overwritten with another Tween, while Clutter considers any
   property change

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/22

js/ui/screenshot.js

@@ -7,7 +7,6 @@ const Signals = imports.signals;
 const GrabHelper = imports.ui.grabHelper;
 const Lightbox = imports.ui.lightbox;
 const Main = imports.ui.main;
-const Tweener = imports.ui.tweener;
 
 const { loadInterfaceXML } = imports.misc.fileUtils;
 
@@ -298,14 +297,12 @@ var SelectArea = class {
 
     _onButtonRelease() {
         this._result = this._getGeometry();
-        Tweener.addTween(this._group,
-                         { opacity: 0,
-                           time: 0.2,
-                           transition: 'easeOutQuad',
-                           onComplete: () => {
-                               this._grabHelper.ungrab();
-                           }
-                         });
+        this._group.ease({
+            opacity: 0,
+            duration: 200,
+            mode: Clutter.AnimationMode.EASE_OUT_QUAD,
+            onComplete: () => this._grabHelper.ungrab()
+        });
         return Clutter.EVENT_PROPAGATE;
     }
 
@@ -382,15 +379,15 @@ var Flashspot = class extends Lightbox.Lightbox {
     fire(doneCallback) {
         this.actor.show();
         this.actor.opacity = 255;
-        Tweener.addTween(this.actor,
-                         { opacity: 0,
-                           time: FLASHSPOT_ANIMATION_OUT_TIME / 1000,
-                           transition: 'easeOutQuad',
-                           onComplete: () => {
-                               if (doneCallback)
-                                   doneCallback();
-                               this.destroy();
-                           }
-                         });
+        this.actor.ease({
+            opacity: 0,
+            duration: FLASHSPOT_ANIMATION_OUT_TIME,
+            mode: Clutter.AnimationMode.EASE_OUT_QUAD,
+            onComplete: () => {
+                if (doneCallback)
+                    doneCallback();
+                this.destroy();
+            }
+        });
     }
 };