Convert Firefox add-on to use the Chrome WebExtension

Here’s a tracking issue to pull in all the related pieces needed to make the current WebExtension work within Firefox. Firefox 57 (coming in November) will be removing support for the add-on SDK and should have full support for all the WebExtension APIs used here.

• chrome.extension.onConnect used here, needs to be updated to use runtime.onConnect
• chrome.extension.onMessage used here needs to be updated to use runtime.onMessage
• chrome.extension.sendMessage used a lot in content-script.js needs to be updated to use runtime.sendMessage

I’ll look through the rest of the errors and keep updating this list as I go.

[clarkbw]

Here’s where the progress is so far: https://github.com/emberjs/ember-inspector/compare/master...clarkbw:firefox-webextension

I’m actually now running into an issue that seems present on Chrome as well as Firefox and prevents the panel from running at all.

[clarkbw]

I’m seeing it here! https://addons.mozilla.org/en-US/firefox/addon/ember-inspector/

🎉 🎈