Bug 1772802 - Load in accountManager.css the platform specific preferences.css. r=mkmelin

Differential Revision: https://phabricator.services.mozilla.com/D148371

--HG--
extra : amend_source : cdac9a62265726f5229b764da04fee92550dfe97

mail/themes/shared/mail/accountManager.css

@@ -8,7 +8,7 @@
 
 @import url("chrome://global/skin/global.css");
 @import url("chrome://global/skin/in-content/common.css");
-@import url("chrome://messenger/skin/shared/preferences/preferences.css");
+@import url("chrome://messenger/skin/preferences/preferences.css");
 
 @media (prefers-contrast) {
   :root {