Comment made by: potetm
After thinking about it some more, I'm not sure what the gain is for being able to specify {{:optimizations}} in the browser-env, and the cost is confusion on the part of the users. I do not think it's apparent that this is a compiler option for the child iframe JS and evaluated repl forms. This may be a case where we can just "do the right thing" and remove some burden from the user.
I'm thinking we either remove {{:optimizations}} entirely or we only use it for evaluated repl forms and use {{:simple}} for the initial payload. Considering the user can already override this in the arguments to {{cljs.repl/repl}}, I lean toward removing it altogether.
