Support for spread operator on JSX element children

TypeScript 2.2 adds support for using spread on a JSX element children. Please see facebook/jsx#57 for more details.

Example

function Todo(prop: { key: number, todo: string }) {
    return <div>{prop.key.toString() + prop.todo}</div>;
}
function TodoList({ todos }: TodoListProps) {
    return <div>
        {...todos.map(todo => <Todo key={todo.id} todo={todo.todo} />)}
    </div>;
}
let x: TodoListProps;
<TodoList {...x} />