Description of problem:

The new '"hasOverview": false' feature is causing errors in gnome extensions.  For example...

In RHEL 7.8 

- login as gnome session and gnome-shell-extension-dash-to-dock will load and is usable
- login as gnome classic session and extension gnome-shell-extension-dash-to-dock fails to load.

If I force downgrade gnome-classic-session-3.28.1-11.el7.noarch.rpm to gnome-classic-session-3.28.1-7.el7.noarch.rpm it appears again.

Something has been modified in gnome-classic-session which prevents this extension from loading.
Lets have a look, the error does not throw up anything of use.

Feb 20 04:27:18 localhost.localdomain gnome-shell[5259]: JS WARNING: [/usr/share/gnome-shell/extensions/dash-to-dock.github.com/docking.js 322]: reference to undefined property "viewSelector"
Feb 20 04:27:18 localhost.localdomain gnome-shell[5259]: Extension "dash-to-dock.github.com" had error: TypeError: Main.overview.viewSelector is undefined

Comparing old vs new bundles of gnome-classic-session we see the following.
Caused by this new "feature"
"hasOverview": false
Changing this to true an dash to dock loads again.

This has been working through all releases of 7x, this is a regression.

--- 1/usr/share/gnome-shell/modes/classic.json
2020-02-20 10:33:56.512040948 +0100
+++ 2/usr/share/gnome-shell/modes/classic.json
2020-02-20 10:34:01.889116419 +0100
@@ -1,8 +1,9 @@
 {
     "parentMode": "user",
     "stylesheetName": "gnome-classic.css",
-    "enabledExtensions": ["alternate-tab.github.com", "apps-menu.github.com", "places-menu.github.com", "launch-new-instance.github.com", "top-icons.github.com", "window-list.github.com"],
-    "panel": { "left": ["activities", "appMenu"],
+    "hasOverview": false,
+    "enabledExtensions": ["alternate-tab.github.com", "apps-menu.github.com", "horizontal-workspaces.github.com", "places-menu.github.com", "launch-new-instance.github.com", "top-icons.github.com", "window-list.github.com"],
+    "panel": { "left": ["appMenu"],
                "center": [],
                "right": ["a11y", "keyboard", "dateMenu", "aggregateMenu"]
              }



Version-Release number of selected component (if applicable):

RHEL 7.8
Gnome Classic


How reproducible:

Repeatedly


Steps to Reproduce:
1. login as gnome classic session and extension gnome-shell-extension-dash-to-dock fails to load.


Actual results:

gnome extensions such as Dash to Dock fail to load in RHEL 7.8 with Gnome Classic session


Expected results:

gnome extensions such as Dash to Dock load successfully in RHEL 7.8 with Gnome Classic session