How to format Handlebars HTML attributes on newlines?

I am using Ember.js from an HAML template.

I would like to format my expression like the following:

{{hamburgermenu-item  id="toolbar-item-import" 
                      title="Import..." 
                      action="doImportAction" 
                      icon="cloud-upload" 
                      label="Upload and import a score"}}

However, Handlebars is giving me a parse error:

Expecting 'CLOSE', 'CLOSE_UNESCAPED', 'STRING', 'INTEGER', 'BOOLEAN', 'OPEN_SEXPR', 'CLOSE_SEXPR', 'ID', 'DATA', got 'INVALID'

Is it possible to format handlebar attributes on newlines like this? I could swear I've seen some people do it..