Bug 1753760 - Rename inc.css files to .css r=dao

Renamed .inc.css files to .css so that the manifest doesn't alter file names.

Differential Revision: https://phabricator.services.mozilla.com/D140764

browser/themes/shared/jar.inc.mn

@@ -226,7 +226,7 @@
   skin/classic/browser/panic-panel/header@2x.png               (../shared/panic-panel/header@2x.png)
   skin/classic/browser/panic-panel/icons.png                   (../shared/panic-panel/icons.png)
   skin/classic/browser/panic-panel/icons@2x.png                (../shared/panic-panel/icons@2x.png)
-  skin/classic/browser/places/sidebar.css                      (../shared/places/sidebar.inc.css)
+  skin/classic/browser/places/sidebar.css                     (../shared/places/sidebar.css)
   skin/classic/browser/places/bookmarksMenu.svg                (../shared/places/bookmarksMenu.svg)
   skin/classic/browser/places/bookmarksToolbar.svg             (../shared/places/bookmarksToolbar.svg)
   skin/classic/browser/places/folder-smart.svg                 (../shared/places/folder-smart.svg)
@@ -235,4 +235,4 @@
   skin/classic/browser/privatebrowsing/aboutPrivateBrowsing.css (../shared/privatebrowsing/aboutPrivateBrowsing.css)
   skin/classic/browser/privatebrowsing/favicon.svg             (../shared/privatebrowsing/favicon.svg)
 
-  skin/classic/browser/syncedtabs/sidebar.css                  (../shared/syncedtabs/sidebar.inc.css)
+  skin/classic/browser/syncedtabs/sidebar.css                  (../shared/syncedtabs/sidebar.css)