Typescript: Give better error messages when reserved names are used for binding identifiers

[zpdDG4gta8XKpMCd]

const data = { in: 1 };
const { in } = data; // <-- [ts] ':' expected.

[RyanCavanaugh]

What are you expecting to happen here? This is an ES6 syntax error and it's not possible to create a local binding named in

[zpdDG4gta8XKpMCd]

a error saying: This is an ES6 syntax error and it's not possible to create a local binding named in or something similar

[DanielRosenwasser]

let delete = 10;

Should also get the same sort of treatment here. Not exactly sure what the parsed syntax tree should look like after this (probably should stay the same), but we could at least give a better error message.

[Dean-NC]