REPL: remove parts of the url that are falsy/empty since unncessary

So for a url like

https://babeljs.io/repl/#?babili=false&browsers=&build=&builtIns=false&code_lz=IZA&debug=false&circleciRepo=&evaluate=false&lineWrap=true&presets=es2015-loose&targets=&version=7.0.0-beta.0

Some of the fields that are either &key= or &key=false can be removed and it should work the same? babili=false&browsers=&build=&builtIns=false&debug=false&circleciRepo=&evaluate=false&targets=

This is because we don’t have default true/false so not setting false should be ok. Basically then we can have a shorter url

(unless we create a button somewhere to shorten the url or something)

[Daniel15]

Instead of stripping false, we should strip params that have the default value. It’s possible we already have params that default to true, or might in the future.

[bvaughn]

Some of the fields that are either &key= or &key=false can be removed and it should work the same?

This is because we don’t have default true/false so not setting false should be ok. Basically then we can have a shorter url

I have concerns about this proposed change, as mentioned in this comment.