Incorrect constraint violation error using `keyof` with generic

[RyanCavanaugh]

TypeScript Version: master

Code

interface HTMLKind {
 "a": HTMLAnchorElement;
 "div": HTMLDivElement;
 "span": HTMLSpanElement;
 "input": HTMLInputElement;
 // ... dozens more ...
 [s: string]: HTMLElement;
}

// Incorrect error on the return type here
declare function getElementsByTagName<T extends keyof HTMLKind>(k: T): NodeListOf<HTMLKind[T]>;

Expected behavior:
No error

Actual behavior:

Type 'HTMLKind[T]' does not satisfy the constraint 'Node'.

[mhegazy]

This is blocking the change to lib.d.ts to reduce symbol instantiations at the moment, see microsoft/TypeScript-DOM-lib-generator#166