MS Edge compatibility

[mazmazz]

Closes #34. Edge loads this extension with the following changes:

• manifest.json: Add author field
• manifest.json: Add background.persistent = false
• background.js: Define chrome.webRequest by pointing to browser.webRequest

It sideloads and works fine in all three browsers.

Packaging and submission info is here; I haven't looked into this personally. (edit: see comment, it works)

[mazmazz]

I think this is the best polyfill because of this compat weirdness:

• Edge defines window.chrome already, but not chrome.webRequest.
• Edge defines browser.webRequest as callback-based.
• Firefox defines chrome.webRequest as callback-based and browser.webRequest as Promise-based.
• Chrome defines chrome.webRequest as callback-based and does NOT define browser.webRequest.

So I could not directly use browser.webRequest because Chrome does not have it and Firefox implements it differently. I also could not do the single-line chrome.webRequest = chrome.webRequest || browser.webRequest because Chrome evaluates both expressions and errors out.

[mazmazz]

background.persistent is required for Edge. Chrome says to use false for background scripts (and I assume this is default).

Firefox outputs this warn message upon side-loading, but otherwise the extension works fine. It comes across as an error, but is actually a warn. See Bugzilla issue on changing this message. I don't think this affects the user install experience, but I'm unfamiliar with that process.

[mazmazz]

Edge extension packaging works. See test package: anti-paywall-9044fce.zip

I followed the instructions here:

• Using ManifoldJS to create extension AppX packages
  • More info about Dev Center identity keys: Creating and testing a Microsoft Edge extension AppX package
• Create a certificate for package signing (You will not need to do this if submitting to the Windows Store)
• Sign an app package using SignTool (Ditto)

For submission, you would need to provide the app icon at 44x44, 50x50, and 150x150. You would also need to sign up with Windows Dev Center and input the supplied Identity keys in the packaging step. See first link for more details.