Upgrade devDependencies: eslint 5->8, mocha 6->9, nyc 14->15

Author: ericyhwang

.eslintrc.js

@@ -1,15 +1,15 @@
 // The ESLint ecmaVersion argument is inconsistently used. Some rules will ignore it entirely, so if the rule has
 // been set, it will still error even if it's not applicable to that version number. Since Google sets these
 // rules, we have to turn them off ourselves.
-const DISABLED_ES6_OPTIONS = {
+var DISABLED_ES6_OPTIONS = {
   'no-var': 'off',
   'prefer-rest-params': 'off',
   'prefer-spread': 'off',
   // Not supported in ES3
   'comma-dangle': ['error', 'never']
 };
 
-const CUSTOM_RULES = {
+var CUSTOM_RULES = {
   'one-var': 'off',
   // We control our own objects and prototypes, so no need for this check
   'guard-for-in': 'off',
@@ -18,7 +18,7 @@ const CUSTOM_RULES = {
   'indent': ['error', 2, {'SwitchCase': 1}],
   // Less aggressive line length than Google, which is especially useful when we have a lot of callbacks in our code
   'max-len': ['error', {code: 120, tabWidth: 2, ignoreUrls: true}],
-  // Google overrides the default ESLint behaviour here, which is slightly better for catching erroneously unused variables
+  // Go back to default ESLint behaviour here, which is slightly better for catching erroneously unused variables
   'no-unused-vars': ['error', {vars: 'all', args: 'after-used'}],
   'require-jsdoc': 'off',
   'valid-jsdoc': 'off'
@@ -27,11 +27,11 @@ const CUSTOM_RULES = {
 module.exports = {
   extends: 'google',
   parserOptions: {
-    ecmaVersion: 3
+    ecmaVersion: 5
   },
   rules: Object.assign(
     {},
     DISABLED_ES6_OPTIONS,
     CUSTOM_RULES
-  ),
+  )
 };

.mocharc.yml

@@ -0,0 +1,4 @@
+reporter: spec
+timeout: 1200
+check-leaks: true
+recursive: true

package.json

@@ -22,10 +22,10 @@
   "devDependencies": {
     "chai": "^4.2.0",
     "coveralls": "^3.0.5",
-    "eslint": "^5.16.0",
-    "eslint-config-google": "^0.13.0",
-    "mocha": "^6.1.4",
-    "nyc": "^14.1.1"
+    "eslint": "^8.1.0",
+    "eslint-config-google": "^0.14.0",
+    "mocha": "^9.1.3",
+    "nyc": "^15.1.0"
   },
   "bugs": {
     "url": "https://github.com/derbyjs/racer/issues"