Fix: operator-assignment removes and duplicates comments

[mdjermanovic]

What is the purpose of this pull request? (put an "X" next to item)

[X] Bug fix

This PR fixes operator-assignment to prevent autofix if it would remove or duplicate comments.

Tell us about your environment

• ESLint Version: 6.5.1
• Node Version: 10.16.0
• npm Version: 6.9.0

What parser (default, Babel-ESLint, etc.) are you using?

default

Please show your full configuration:

Configuration

module.exports = {
  parserOptions: {
    ecmaVersion: 2015,
  }
};

What did you do? Please include the actual source code causing the issue.

Online Demo Link 1

/* eslint operator-assignment: ["error", "always"]*/

x = /* comment */ x + y;

x = x // comment 
	+ y;

Online Demo Link 2

/* eslint operator-assignment: ["error", "never"]*/

x /* comment */ += y;

x // comment
	+= y;

What did you expect to happen?

Not to remove/duplicate comments.

What actually happened? Please include the actual, raw output from ESLint.

/* eslint operator-assignment: ["error", "always"]*/

x += y;

x += y;

/* eslint operator-assignment: ["error", "never"]*/

x /* comment */ = x /* comment */ + y;

x // comment
	= x // comment
	+ y;

What changes did you make? (Give an overview)

Check for the comments in the ranges there are going to be removed or copied to prevent fixing.

Is there anything you'd like reviewers to focus on?

[kaicataldo]

LGTM, thanks!

[btmills]

LGTM