Bug 1494135: Add the `page_action.pinned` property (#2906)
Bug 1494135: Add the `page_action.pinned` property (#2906)

# External links:
- https://bugzil.la/1494135
chrisdavidmills/browser-compat-data,mdn/browser-compat-data,chrisdavidmills/browser-compat-data,mdn/browser-compat-data