Make 'file' in unknown content dialog localizable. Bug 340038, r=mano

toolkit/locales/en-US/chrome/mozapps/downloads/unknownContentType.properties

@@ -46,3 +46,4 @@ selectDownloadDir=Select Download Folder
 myDownloads=My Downloads
 unknownAccept.label=Save File
 unknownCancel.label=Cancel
+fileType=%S file

toolkit/mozapps/downloads/src/nsHelperAppDlg.js.in

@@ -569,7 +569,7 @@ nsUnknownContentTypeDialog.prototype = {
           catch (ex) {
           }
           if (primaryExtension != "")
-            typeString = primaryExtension.toUpperCase() + " file";
+            typeString = this.dialogElement("strings").getFormattedString("fileType", [primaryExtension.toUpperCase()]);
           // 3. If we can't even do that, just give up and show the MIME type. 
           else
             typeString = mimeInfo.MIMEType;