Remove unused code

[jasonLaster]

It's pretty common to get unreachable code warnings in our mochitests. We should remove these because dead code is extra kb and it fills up the logs.

Babel has a useful plugin, which we should be able to use.

https://babeljs.io/docs/plugins/minify-dead-code-elimination/

2252 INFO Console message: [JavaScript Warning: "unreachable code after return statement" {file: "resource://devtools/client/debugger/new/parser-worker.js" line: 22801}]

[jasonLaster]

I started this branch to add uglify which looks like it should be perfect... but no luck

https://github.com/webpack-contrib/uglifyjs-webpack-plugin

https://github.com/jasonLaster/devtools-core/tree/uglify

[wldcordeiro]

@jasonLaster uglify has had its troubles with ES6/Babel code. Might be worth fiddling with babili? https://github.com/babel/babili

[zaggy]

@wldcordeiro, I would vote for uglify for the reason that code minification probably should be a part of the webpack pipeline and not a part of just one of the tasks. It is more future proof if we would like to add or change something in the webpack pipeline (typescript, maybe).

[wldcordeiro]

@zaggy we've put a lot of work into using Flow so I'm doubtful of Typescript being included. 😉