Bug 1701691 - about:logins -moz-toolbar-prefers-color-scheme support r=sfoster

Differential Revision: https://phabricator.services.mozilla.com/D111973

browser/components/aboutlogins/content/aboutLogins.css

@@ -77,7 +77,7 @@ login-item {
   fill: #20123a;
 }
 
-@media (prefers-color-scheme: dark) {
+@media (-moz-toolbar-prefers-color-scheme: dark) {
   #branding-logo {
     fill: #fff;
   }

browser/components/aboutlogins/content/components/login-item.css

@@ -13,13 +13,13 @@
 }
 
 /* Only overwrite the deemphasized text color in non-dark mode. */
-@media not (prefers-color-scheme: dark) {
+@media not (-moz-toolbar-prefers-color-scheme: dark) {
   :host {
     --in-content-deemphasized-text: #737373;
   }
 }
 
-@media (prefers-color-scheme: dark) {
+@media (-moz-toolbar-prefers-color-scheme: dark) {
   :host {
     --reveal-checkbox-opacity: .8;
     --reveal-checkbox-opacity-hover: 1;