Import upstream changes (7d185b4e882aeca70c7b750d8295d0da34a09cd8)
Import upstream changes (7d185b4e882aeca70c7b750d8295d0da34a09cd8)

lit/lit-element-starter-ts,PolymerLabs/lit-element-starter-ts,PolymerLabs/lit-element-starter-ts,PolymerLabs/lit-element-starter-ts,lit/lit-element-starter-ts,lit/lit-element-starter-ts