Console errors when editing page title

Problem/Motivation

The attached patch fixes a couple of console errors observed when editing a page title.

In js/inline-editor.parent.sync.js the error is caused by a reference to a variable called syncId that isn't initialized. I've copied the value from the function above it; but please validate that this has the correct/intended value.

In inline-editor.preview.sync.js I've added some code hardening that checks that the inputField exists before attempting to get its attribute value.

Steps to reproduce

Alter the page title and observe browser console

Proposed resolution

Patch attached.