Add attribute to indicate whether element has value or not

[ainvaltin]

Add an attribute/property which indicates whether the input is empty or not. Intended usage is in CSS selectors ie

paper-chip-input-autocomplete[has-value] {...}

Unfortunately it seems that the standard :placeholder-shown class is not working with polymer elements (ie even with paper-input).
Vaadin elements do have (at least combo-box and date-picker) hasValue property for this purpose.

[ThomasStrohm]

You can check the length of the property items in paper-chip-input-autocomplete.

[ainvaltin]

Could check the items.length in code, but how to write it in CSS? Ie

  paper-chip-input-autocomplete[not(items.length=0)]{
     --paper-chip-autocomplete-focus-color: yellow;
  }

doesn't work.