`string[]` cannot be used instead of `DOMStringList`

[falsandtru]

DOMStringList has some methods different from string[] such as constains and item. So we need to revert microsoft/TypeScript-DOM-lib-generator#148 by next release 2.1.0.

TypeScript Version: 2.1.0-dev.20161106

Code

interface DOMStringList {
    readonly length: number;
    contains(str: string): boolean;
    item(index: number): string | null;
    [index: number]: string;
}

cc @mhegazy