fix: inject polyfill earlier when `world: MAIN` is supported

sidvishnoi commented 2 months ago

Context

Fixes https://github.com/interledger/web-monetization-extension/issues/590 Without needing to sacrifice Firefox support!

Changes proposed in this pull request

If browser supports world: MAIN for content script, we inject directly using scripting.registerContentScripts API (can detect WM support immediately on page load). If not, we inject like before from contentScript (slow, requires timeout for WM support detection).

We inject via scripting.registerContentScripts API and not directly via manifest.json, as we can catch the lack of support of world: MAIN via this API. With this detection, we can still support Firefox versions older than 128.

Update polyfill to support injecting twice - only the first injection works - as we detect if already injected.

Note: In content script, we inject polyfill from contentScript and not using scripting.executeScript in background as we'd otherwise need to inject it manually to each tab.

What next?

When Firefox 128 is old enough, we can remove injectPolyfill from background.ts as well as contentScript.ts and register it directly in manifest.json with world: MAIN. When we do that, we'd update browser_specific_settings.gecko.strict_min_version in manifest.json from 110 to 128, and also remove polyfill/* from web_accessible_resources. (https://github.com/interledger/web-monetization-extension/issues/607)