DevTools: Introduce eslint configuration.

third_party/WebKit/Source/devtools/front_end/.eslintrc.js

+module.exports = {
+    "root": true,
+
+    "env": {
+        "browser": true,
+        "es6": true
+    },
+
+    /**
+     * ESLint rules
+     *
+     * All available rules: http://eslint.org/docs/rules/
+     *
+     * Rules take the following form:
+     *   "rule-name", [severity, { opts }]
+     * Severity: 2 == error, 1 == warning, 0 == off.
+     */
+    "rules": {
+
+        /**
+         * Enforced rules
+         */
+
+        // syntax preferences
+        "quotes": [2, "double", {
+            "avoidEscape": true,
+            "allowTemplateLiterals": true
+        }],
+        "comma-style": [2, "last"],
+        "wrap-iife": [2, "inside"],
+        "yoda": [2, "never"],
+        "spaced-comment": [2, "always", {
+            "markers": ["*"]
+        }],
+        "arrow-body-style": [2, "as-needed"],
+        "accessor-pairs": [2, {
+            "getWithoutSet": false,
+            "setWithoutGet": false
+        }],
+        "handle-callback-err": 2,
+        "id-blacklist": 2,
+        "id-match": 2,
+        "max-nested-callbacks": 2,
+
+        // anti-patterns
+        "no-with": 2,
+        "no-multi-str": 2,
+        "no-caller": 2,
+        "no-implicit-coercion": [2, {
+            "boolean": false,
+            "number": false,
+            "string": false
+        }],
+        "no-implied-eval": 2,
+        "no-label-var": 2,
+        "no-new-object": 2,
+        "no-octal-escape": 2,
+        "no-self-compare": 2,
+        "no-shadow-restricted-names": 2,
+
+        // es2015 features
+        "no-useless-constructor": 2,
+        "require-yield": 2,
+        "yield-star-spacing": 2,
+        "sort-imports": 2,
+        "template-curly-spacing": [2, "never"],
+
+        // spacing details
+        "space-infix-ops": 2,
+        "space-in-parens": [2, "never"],
+        "space-before-function-paren": [ 2, "never" ],
+        "no-whitespace-before-property": 2,
+        "space-unary-ops": [2, {
+            "words": false,
+            "nonwords": false
+        }],
+        "keyword-spacing": [2,{
+            "overrides": {
+            "if": {"after": true},
+            "else": {"after": true},
+            "for": {"after": true},
+            "while": {"after": true},
+            "do": {"after": true},
+            "switch": {"after": true},
+            "return": {"after": true}
+            }
+        }],
+        "arrow-spacing": [
+            2,
+            {
+                "after": true,
+                "before": true
+            }
+        ],
+
+        // file whitespace
+        "no-multiple-empty-lines": 2,
+        "no-mixed-spaces-and-tabs": 2,
+        "no-trailing-spaces": 2,
+        "eol-last": 2,
+        "linebreak-style": [ 2, "unix" ],
+
+
+        /**
+         * Disabled, aspirational rules
+         */
+
+        // brace-style is disabled, as eslint cannot enforce 1tbs as default, but allman for functions
+        "brace-style": [0, "allman", { "allowSingleLine": true }],
+
+        // key-spacing is disabled, as some objects use value-aligned spacing, some not.
+        "key-spacing": [0, {
+            "beforeColon": false,
+            "afterColon": true,
+            "align": "value"
+        }],
+        // quote-props is diabled, as property quoting styles are too varied to enforce.
+        "quote-props": [0, "as-needed"],
+
+        // no-implicit-globals will prevent accidental globals
+        "no-implicit-globals": [0]
+
+    }
+};