[gnome-shell] windowPreview: Remove slotId property

[Florian Müllner <fmuellner src gnome org>]

commit 89574abc83b9a90076f213bda5b0705f483d1d7d
Author: Jonas Dreßler <verdre v0yd nl>
Date:   Tue Jul 7 11:21:02 2020 +0200

    windowPreview: Remove slotId property
    
    We're no longer using that property, so clean up a bit and remove the
    last occurences of it.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1351

 js/ui/windowPreview.js | 1 -
 js/ui/workspace.js     | 2 --
 2 files changed, 3 deletions(-)
---
diff --git a/js/ui/windowPreview.js b/js/ui/windowPreview.js
index c5510e4c1a..48d42c87d3 100644
--- a/js/ui/windowPreview.js
+++ b/js/ui/windowPreview.js
@@ -229,7 +229,6 @@ var WindowPreview = GObject.registerClass({
 
         this._delegate = this;
 
-        this.slotId = 0;
         this._stackAbove = null;
 
         this._windowContainer.layout_manager.connect(
diff --git a/js/ui/workspace.js b/js/ui/workspace.js
index d2bbfc299d..e1b5ea7a8f 100644
--- a/js/ui/workspace.js
+++ b/js/ui/workspace.js
@@ -601,8 +601,6 @@ var WorkspaceLayout = GObject.registerClass({
             const [x, y, width, height] = this._windowSlots[index];
             const windowInfo = this._windows.get(child);
 
-            child.slotId = index;
-
             if (windowInfo.metaWindow.showing_on_its_workspace()) {
                 workspaceBox.x1 = child.boundingBox.x - this._workarea.x;
                 workspaceBox.x2 = workspaceBox.x1 + child.boundingBox.width;