Quote preference not used for literal type completions

[jrieken]

• use single quote preference
• have the snippet below, trigger intellisense
• 🐛 double quotes are used

type Foo = 'abc' | 'def';

let f: Foo = 

[mjbvz]

Confirmed with typescript@3.5.0-dev.20190521

[DanielRosenwasser]

Thanks @a-tarasyuk!