ToDo: Document how to get Firefox to run from source

[gamebeaker]

Problem in firefox desktop and firefox android

Firefox.js -> injectContentScript() -> chrome.tabs.executeScript
fails with:

It only happens if WebToEpub is loaded from the unzipped file (open manifest.json instead of xpi)
The main problem is in firefox android as i can only debug the unzipped version and not the xpi version. As result of that the dom is unavailable to debug.

The xpi version which is downloaded from the store works as intended.

[dteviot]

@gamebeaker
IIRC, you can't use the source directly in Firefox. Need to build the xpi and then unzip.
To start with, Firefox is using manifest v2, chrome is v3. So, build script will re-write manifest.json
https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/tabs/executeScript

I need to update the documentation.

[gamebeaker]

@dteviot thanks it works for desktop and android.