This repo contains a pair of extensions and one demo webapp.

• experiment directory contains the source of the experimental WebExtensions API for passing Reflect.parse API into WebExtensions. Install it first. nightly.link
• extension directory contains a simple extension injecting the API into every webpage. nightly.link
• page contains a simple webapp parsing JS source into an AST and showing that AST as pretty-printed JSON. Unfortunately, document_start doesn't work, so the app will likely say that the API is not present.

To install the WebExtensions Experiments into a regular (non-Developer Edition, non-Nightly) Firefox you need to patch it. I have created a tool to do it.