Changed

• LitElement changed to a non-abstract class to be more compatible with the JavaScript mixin pattern (#227).
• Update lit-html dependency to ^0.12.0 (#244).
• Passes the component's this reference to lit-html as the eventContext, allowing unbound event listener methods (#244).

Added

• A disconnectedCallback() method was added to UpdatingElement (#213).
• Added @eventOptions() decorator for setting event listener options on methods (#244).