Não foi possível só com a alteração do let para var - estou usando a versão 5.1.7 e esta sendo criticado a palavra reservada class na declaração das classes
SyntaxError: Use of reserved word 'class'
Mensagem.js:1SyntaxError: Use of reserved word 'class'
NegociacaoController.js:1SyntaxError: Use of reserved word 'class'
DateHelper.js:1SyntaxError: Use of reserved word 'class'
ListaNegociacoes.js:1SyntaxError: Use of reserved word 'class'
View.js:1SyntaxError: Use of reserved word 'class'
NegociacoesView.js:1SyntaxError: Use of reserved word 'class'
MensagemView.js:1SyntaxError: Use of reserved word 'class'
ProxyFactory.js:1SyntaxError: Use of reserved word 'class'
Bind.js:1SyntaxError: Use of reserved word 'class'
NegociacaoService.js:1SyntaxError: Use of reserved word 'class'
HttpService.js:1SyntaxError: Use of reserved word 'class'
:3000/:65ReferenceError: Can't find variable: NegociacaoController
:3000/:134SyntaxError: Expected an identifier but found 'negociacaoProxy' instead
:3000/:158SyntaxError: Expected an identifier but found 'lista' instead
:3000/:41TypeError: 'undefined' is not an object (evaluating 'negociacaoController.importaNegociacoes')
