Remove unused files. Add a dtd file for sidebar.rdf.

xpfe/components/sidebar/resources/locale/MANIFEST

@@ -2,7 +2,6 @@ en-US:customize-panel.dtd
 en-US:customize.dtd
 en-US:flash.dtd
 en-US:preview.dtd
-en-US:sidebar-browser-rdf.dtd
-en-US:sidebar-browser.dtd
 en-US:sidebar-registry-rdf.dtd
+en-US:sidebar-rdf.dtd
 en-US:sidebarOverlay.dtd

xpfe/components/sidebar/resources/locale/en-US/sidebar-rdf.dtd

@@ -0,0 +1,7 @@
+<!-- extracted from ./sidebar.rdf -->
+
+<!ENTITY sidebar.whats-related.label  "What's Related">
+<!ENTITY sidebar.alerts.label         "Alerts">
+<!-- LOCALIZATION NOTE  sidebar.tinderbox.label: Do NOT localize the term "Tinderbox"  -->
+<!ENTITY sidebar.tinderbox.label      "Tinderbox">
+<!ENTITY sidebar.bookmarks.label      "Bookmarks">