Administration: Add missing :before to two Dashicon class definitions.

Introduced in [45040].

Props builtbynorthby.
Fixes #41074.

git-svn-id: https://develop.svn.wordpress.org/trunk@45225 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/css/dashicons.css

@@ -1138,7 +1138,8 @@
 	content: "\f211";
 }
 
-.dashicons-exerpt-view {
+/* This is a typo, but was previously released. It should remain for backward compatibility. See https://core.trac.wordpress.org/ticket/30832. */
+.dashicons-exerpt-view:before {
 	content: "\f164";
 }
 
@@ -1150,7 +1151,7 @@
 	content: "\f109";
 }
 
-.dashicons-post-trash {
+.dashicons-post-trash:before {
 	content: "\f182";
 }