From what i understand the part 16 of the Space Shooter Tutorial is outdated an the PDF that is used to update the tutorial does not mention anything about that.
For security reasons, WebGL applications can’t be launched in local. They have to be hosted on a server.
If you don’t have a server, and if you don’t want to buy one, I suggest you installing a web development environment in order to have a local server on your computer. Don’t worry, it’s very easy
You have several possibilities, depending on your OS. On Windows, you can use EasyPHP or Wamp.
Once you have installed the software, launch it and copy-paste your WebGL project in a special folder ( <path_to_wamp>/www or <path_to_easy_php>/eds-www). Then, type localhost/<webGL_folder_name>) in your browser and you are done !
Otherwise, run Chrome with the --allow-file-access-from-files flag. To do so, you can: