There are a couple of other ways to mitigate the problem for web applications. If you're willing to install a browser extension, then it might make more sense to use the Signed Pages extension[0] which applies PGP signature checking to web pages. The other solution is to use Secure Bookmarks[1], which combine SRI integrity hashes with Data URIs to ensure that a fixed bundle of JavaScript is running in the page.

[0] https://github.com/tasn/webext-signed-pages

[1] https://coins.github.io/secure-bookmark/