tools: enable more eslint rules

This commit enables these new in ESLint 6.7.0 rules:

- no-constructor-return
- no-dupe-else-if
- no-setter-return

PR-URL: #30598
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

Author: cjihrig

.eslintrc.js

@@ -118,12 +118,14 @@ module.exports = {
     'no-class-assign': 'error',
     'no-confusing-arrow': 'error',
     'no-const-assign': 'error',
+    'no-constructor-return': 'error',
     'no-control-regex': 'error',
     'no-debugger': 'error',
     'no-delete-var': 'error',
     'no-dupe-args': 'error',
     'no-dupe-class-members': 'error',
     'no-dupe-keys': 'error',
+    'no-dupe-else-if': 'error',
     'no-duplicate-case': 'error',
     'no-duplicate-imports': 'error',
     'no-empty-character-class': 'error',
@@ -247,6 +249,7 @@ module.exports = {
     'no-return-await': 'error',
     'no-self-assign': 'error',
     'no-self-compare': 'error',
+    'no-setter-return': 'error',
     'no-shadow-restricted-names': 'error',
     'no-tabs': 'error',
     'no-template-curly-in-string': 'error',