fix for bug #342930: "You have asked to open [lots of] tabs at once" should read "You are about to open..."

backporting the fix from the MOZILLA_1_8_BRANCH to work on the trunk (both with places enabled and without)

r=dietrich, original patch r=mconnor, ui-r=beltzner

browser/base/content/tabbrowser.xml

@@ -1275,7 +1275,7 @@
             if (!aAll)
               --tabsToClose;
 
-            var messageKey = (tabsToClose == 1) ? "tabs.closeWarningOne" : "tabs.closeWarningMultiple";
+            var messageKey = (tabsToClose == 1) ? "tabs.closeWarningOneTab" : "tabs.closeWarningMultipleTabs";
             var closeKey = (tabsToClose == 1) ? "tabs.closeButtonOne" : "tabs.closeButtonMultiple";
             // focus the window before prompting.
             // this will raise any minimized window, which will

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

@@ -7,8 +7,8 @@ browsewithcaret.checkWindowTitle=Caret Browsing
 browsewithcaret.checkLabel=Pressing F7 turns Caret Browsing on or off. This feature places a moveable cursor in web pages, allowing you to select text with the keyboard. Do you want to turn Caret Browsing on?
 browsewithcaret.checkButtonLabel=Yes
 tabs.closeWarningTitle=Confirm close
-tabs.closeWarningOne=You are about to close %S open tab. Are you sure you want to continue?
-tabs.closeWarningMultiple=You are about to close %S open tabs. Are you sure you want to continue?
+tabs.closeWarningOneTab=You are about to close %S tab. Are you sure you want to continue?
+tabs.closeWarningMultipleTabs=You are about to close %S tabs. Are you sure you want to continue?
 tabs.closeButtonOne=Close tab
 tabs.closeButtonMultiple=Close tabs
-tabs.closeWarningPromptMe=Warn me when I attempt to close multiple tabs
+tabs.closeWarningPromptMe=Warn me when I attempt to close multiple tabs