Toolbar: Add search icon prefix to command palette item in admin bar.

Displays a search icon before the shortcut text in desktop view to clarify the item's purpose.

Follow-up to [61912], [61979].

Props sabernhardt, siliconforks, presskopp, westonruter, wildworks.
See #64672.

git-svn-id: https://develop.svn.wordpress.org/trunk@62092 602fd350-edb4-49c9-b593-d223f7449a82

Author: t-hamano

src/wp-includes/css/admin-bar.css

@@ -697,13 +697,10 @@ html:lang(he-il) .rtl #wpadminbar * {
 /**
  * Command Palette
  */
-#wpadminbar #wp-admin-bar-command-palette .ab-icon {
-	display: none; /* Icon displayed only on mobile */
-}
-
 #wpadminbar #wp-admin-bar-command-palette .ab-icon:before {
 	content: "\f179";
 	content: "\f179" / '';
+	top: 3px;
 }
 
 #wpadminbar #wp-admin-bar-command-palette kbd {
@@ -958,10 +955,6 @@ html:lang(he-il) .rtl #wpadminbar * {
 		margin: 0;
 	}
 
-	#wpadminbar #wp-admin-bar-command-palette .ab-icon {
-		display: block; /* Icon is only shown on mobile, while the keyboard shortcut is hidden */
-	}
-
 	#wpadminbar #wp-admin-bar-comments .ab-icon:before,
 	#wpadminbar #wp-admin-bar-command-palette .ab-icon:before {
 		display: block;