Pass value in on-iron-localstorage-load callback

[alexclarkofficial]

It would be nice if the on-iron-localstorage-load callback had the value passed in to more easily do a data-down/actions-up flow.

You could set the value of your prop in the on-iron-localstorage-load callback when the local storage is first read (without querying the DOM, like you would have to do now), and then use a one-way data-binding to write to local storage any changes that happen in your component.