There are a few places in the code that use $.extend() to copy the entire Strings Object like this:

        var templateVars = $.extend({
            title        : title,
            baseUrl      : baseUrl,
            errorMessage : errorMessage
        }, Strings);

Instead, it should be passed by reference:

        var templateVars = {
            title        : title,
            baseUrl      : baseUrl,
            errorMessage : errorMessage,
            Strings      : Strings
        };

Note that string references in dialog templates also need to be updated from SOME_STRING to Strings.SOME_STRING.

Some of the files that need to be updated:

• help/HelpCommandHandlers.js
• utils/UpdateNotification.js
• extensions/default/RecentProjects/main.js
• extensions/default/WebPlatformDocs/InlineDocsViewer.js