Issue 3692 - Add base ESLint configuration

eslint-config-eyeo/index.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2017 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 32 matching lines @@
     "keyword-spacing": "error",
     "linebreak-style": "error",
     "lines-around-directive": "error",
     "max-len": ["error", 80, {ignoreUrls: true}],
     "new-parens": "error",
     "no-array-constructor": "error",
     "no-caller": "error",
     "no-case-declarations": "off",
     "no-catch-shadow": "error",
     "no-cond-assign": "off",
     "no-console": ["error", {allow: ["warn", "error", "trace"]}],

[Sebastian Noack, 2017/02/15 10:35:24]

We discussed that before, but I just noticed that you ignored my last comment on
that debate in the other review. Do we have any legit use of console.warn() and
console.trace() in our code? In particular console.trace() seems to be mostly
useful for debugging, with a similar chance as console.log() to be added
temporarily and then being forgotten.

[kzar, 2017/02/15 11:45:20]

console.trace is used here:
https://github.com/adblockplus/adblockpluschrome/blob/master/lib/compat.js#L83

As for console.warn I don't see that in any of our code, but we should probably
use it in this code that currently uses console.log:
https://github.com/adblockplus/adblockpluscore/blob/master/lib/rsa.js#L143

[Sebastian Noack, 2017/02/15 11:58:05]

Acknowledged.

     "no-control-regex": "off",
     "no-else-return": "error",
+    "no-empty": ["error", {allowEmptyCatch: true}],
     "no-eval": "error",
     "no-extra-bind": "error",
     "no-extra-label": "error",
     "no-implied-eval": "error",
     "no-labels": ["error", {allowLoop: true}],
     "no-lone-blocks": "error",
     "no-lonely-if": "error",
     "no-multi-spaces": "error",
     "no-new-func": "error",
     "no-new-object": "error",
@@ skipping 38 matching lines @@
     "strict": ["error", "global"],
     "valid-jsdoc": ["error", {
       requireParamDescription: false,
       requireReturn: false,
       requireReturnDescription: false
     }],
     "yield-star-spacing": "error",
     "yoda": "error"
   }
 };