Revert "Start WebExtension immediately"
Revert "Start WebExtension immediately"

This reverts commit 81a567a99c83b52cbd61c606e279da308e3d77df.

mozilla-services/screenshots,mozilla-services/screenshots,mozilla-services/screenshots,mozilla-services/pageshot,mozilla-services/pageshot,mozilla-services/pageshot,mozilla-services/screenshots,mozilla-services/pageshot