This adds support for the world:"MAIN" option to the following parts of
the scripting API, including tests:
- scripting.executeScript
- scripting.getRegisteredContentScripts
- scripting.registerContentScripts
- scripting.updateContentScripts
- scripting.ExecutionWorld.MAIN
This patch includes a minimal prototype for scripting.executeScript with
the func parameter, which does not work when the page has a CSP. This
functionality will be improved in the next patch.
Differential Revision: https://phabricator.services.mozilla.com/D211868
51c86fd6b7