Changes names on messenger.com.

Messenger Anonymize.js

// Gets all the names
var names = document.getElementsByClassName("_1ht6");
var nameHeaders = document.getElementsByClassName("_3oh-");

// New name variable, leave empty to delete names (not recommended)
var newName = "";

// Changes names to newName
[].slice.call(names).forEach( function ( name ) { name.innerHTML = newName;});
// Changes nameHeaders and conversation messages to John Doe
[].slice.call(nameHeaders).forEach( function ( name ) { name.innerHTML = newName;});