Save initial files into cache storage instead of browser's cache

At this time, there is no way to save intial files which are fetched at the very first HTTP request into CacheStorage. I'm thinking about having a header that handles this issue.

Cache-Control : location=cache-storage

Then developers can easily retrieve those files saved in cache storage on client side.

CacheStrorage.open('main').then(cache => {
    cache.match('/path/to/initFile').then(response => {
        console.log('File exists in cache storage');
    });
});

Start by examining the proposed Cache-Control: location=cache-storage behavior and how initial files from the first HTTP request relate to CacheStorage. Done means developers can retrieve those initial files through CacheStorage on the client side; the issue does not name files or tests to run.