Bug 947353 - Use proper plural form for tabs.closeWarningMultipleTabs. r=dao

browser/base/content/tabbrowser.xml

@@ -1708,11 +1708,13 @@
           // solve the problem of windows "obscuring" the prompt.
           // see bug #350299 for more details
           window.focus();
+          var warningMessage =
+            PluralForm.get(tabsToClose, bundle.getString("tabs.closeWarningMultiple"))
+                      .replace("#1", tabsToClose);
           var buttonPressed =
             ps.confirmEx(window,
                          bundle.getString("tabs.closeWarningTitle"),
-                         bundle.getFormattedString("tabs.closeWarningMultipleTabs",
-                                                   [tabsToClose]),
+                         warningMessage,
                          (ps.BUTTON_TITLE_IS_STRING * ps.BUTTON_POS_0)
                          + (ps.BUTTON_TITLE_CANCEL * ps.BUTTON_POS_1),
                          bundle.getString("tabs.closeButtonMultiple"),

browser/locales/en-US/chrome/browser/tabbrowser.properties

@@ -21,6 +21,11 @@ tabs.emptyTabTitle=New Tab
 tabs.closeTab=Close Tab
 tabs.close=Close
 tabs.closeWarningTitle=Confirm close
-tabs.closeWarningMultipleTabs=You are about to close %S tabs. Are you sure you want to continue?
+# LOCALIZATION NOTE (tabs.closeWarningMultiple):
+# Semicolon-separated list of plural forms. See:
+# http://developer.mozilla.org/en/docs/Localization_and_Plurals
+# The singular form is not considered since this string is used only for
+# multiple tabs.
+tabs.closeWarningMultiple=;You are about to close #1 tabs. Are you sure you want to continue?
 tabs.closeButtonMultiple=Close tabs
 tabs.closeWarningPromptMe=Warn me when I attempt to close multiple tabs