rtl-text-plugin fails to load if CSP for website doesn't allow script-src: blob:

[arindam1993]

mapbox-gl-js version: 1.6.0

browser: All

Steps to Trigger Behavior

1. Set a page's CSP to not allow script-src: blob:

Cause

Side effect of #8865 , which made a change so that the Main thread now requests the rtl-text-plugin, and generates a blob-url. It then sends the blobURL over to the worker for loading with importScripts. Prior to #8865 each worker would directly use the main url to load the rtl text plugin via importScripts directly, which would lead to multiple parallel network requests and slower load times.

However now, if the parent page doesnt allow script-src: blob: the importScripts for the blobURL will fail and causes rtl text to not be rendered.