workspace: Fade in instead of zoom to return desktop

The zooming animation of the windows looks nice when animating
from the workspace display page, but looks weird from other pages
like apps page or search page since the windows come from nowhere
with an initial position not known to the user.

Instead of that just fade the desktop with the windows in its
original position.

https://bugzilla.gnome.org/show_bug.cgi?id=732901

js/ui/overview.js

@@ -623,7 +623,7 @@ const Overview = new Lang.Class({
         this.animationInProgress = true;
         this.visibleTarget = false;
 
-        this.viewSelector.zoomFromOverview();
+        this.viewSelector.animateFromOverview();
 
         // Make other elements fade out.
         Tweener.addTween(this._stack,