Question, even if Google were to actually do this, given that GMail runs on server-provided JS code inside the browser, doesn't this carry the same problems as

Question, even if Google were to actually do this, given that GMail runs on server-provided JS code inside the browser, doesn't this carry the same problems as all other in-browser encryption applications? Isn't this type of in-browser encryption code considered broken, no matter what way you go about it?