Fix advanced configuration of Layout Widget Editor

Steps to reproduce:
In Studio:

• Configure a custom document with custom schema.
• Add the fields from the custom schema to each of the custom document's layouts.
• On the edit layout, select one of the custom fields and click on the pencil icon to open the Layout Widget Editor.
• Scroll down to Advanced mode configuration and click in the blank space below the heading to make the textbox appear.
• Enter the following:

   #{layoutValue.dc.title=='Hide me' ? 'hidden' : 'edit'}
  

• Save and deploy.

In Nuxeo:

• Create the custom document, with the title "Hide me".
• Edit the document.
  => The custom field is visible, not hidden.
  => The custom field is not editable.

I am not sure about this test scenario – expected results were not made clear, but it seems like the field should be hidden.