Bug 1818282 - Remove an icon that used to be invisible. r=desktop-theme-reviewers,sfoster

This icon has a viewbox, but not a width/height, so it was invisible
with old XUL images because XUL didn't know about image aspect-ratio.

Remove to keep the previous behavior.

Differential Revision: https://phabricator.services.mozilla.com/D170675

browser/themes/shared/customizableui/panelUI-shared.css

@@ -759,10 +759,6 @@ toolbarbutton[constrain-size="true"][cui-areatype="panel"] > .toolbarbutton-badg
   list-style-image: url(chrome://browser/skin/fxa/monitor.svg);
 }
 
-#PanelUI-fxa-menu-connect-device-button {
-  list-style-image: url(chrome://browser/skin/fxa/add-device.svg);
-}
-
 :root:not([fxastatus="signedin"]) #PanelUI-fxa-menu-connect-device-button {
   color: var(--panel-disabled-color);
 }

browser/themes/shared/fxa/add-device.svg

@@ -1,4 +0,0 @@
-<!-- This Source Code Form is subject to the terms of the Mozilla Public
-   - License, v. 2.0. If a copy of the MPL was not distributed with this
-   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16"><path fill="context-fill" fill-opacity="context-fill-opacity" d="M14 5h-3a2 2 0 0 0-2 2v6a2 2 0 0 0 2 2h3a2 2 0 0 0 2-2V7a2 2 0 0 0-2-2zm-3 8V7h3v6z"/><path fill="context-fill" fill-opacity="context-fill-opacity" d="M2 3h8v1h2V3a2 2 0 0 0-2-2H2a2 2 0 0 0-2 2v6a2 2 0 0 0 2 2h3v1H3a1 1 0 0 0 0 2h5v-2H7v-1h1V9H2z"/></svg>

browser/themes/shared/jar.inc.mn

@@ -139,7 +139,6 @@
   skin/classic/browser/fxa/sync-devices.svg                    (../shared/fxa/sync-devices.svg)
   skin/classic/browser/fxa/send.svg                            (../shared/fxa/send.svg)
   skin/classic/browser/fxa/monitor.svg                         (../shared/fxa/monitor.svg)
-  skin/classic/browser/fxa/add-device.svg                      (../shared/fxa/add-device.svg)
 
   skin/classic/browser/fullscreen/warning.css                  (../shared/fullscreen/warning.css)