Continuing #88 where a bug was introduces, here are the essence of the changes:

• On Figma I learned that sometimes websites create blobs with no type ("") so added that as legit blob type
• Also there's a new behaviour in Chrome where creating a URL out of a blob where the URL object belongs to a no longer attached realm returns "" instead of a legit blob url, so i fixed that to make sure URL creation is executed against the top main realm
• Added a test to make sure blob with no type cannot be used as html to bypass snow