TypeScript wrong WebCrypto Algorithm params

[microshine]

TypeScript Version: 2.8.1

Search Terms:
WebCrypto, Algorithm

Problem
iv is required param for AesGcmParams in WebCrypto API, but TypeScript allows to use null value for it
The same problem for another algorithms like AesCbcParams, AesCtrParams, etc.

WebCrypto API https://www.w3.org/TR/WebCryptoAPI/#aes-gcm-params

dictionary AesGcmParams : Algorithm {
  // The initialization vector to use. May be up to 2^64-1 bytes long.
  required BufferSource iv;
  // The additional authentication data to include.
  BufferSource additionalData;
  // The desired length of the authentication tag. May be 0 - 128.
  [EnforceRange] octet tagLength;
};

TypeScript https://github.com/Microsoft/TypeScript/blob/master/lib/lib.dom.d.ts#L51-L55

interface AesGcmParams extends Algorithm {
    additionalData?: Int8Array | Int16Array | Int32Array | Uint8Array | Uint16Array | Uint32Array | Uint8ClampedArray | Float32Array | Float64Array | DataView | ArrayBuffer | null;
    iv: Int8Array | Int16Array | Int32Array | Uint8Array | Uint16Array | Uint32Array | Uint8ClampedArray | Float32Array | Float64Array | DataView | ArrayBuffer | null;
    tagLength?: number;
}

[mhegazy]

PRs welcomed. You can find more information about contributing lib.d.ts fixes at https://github.com/Microsoft/TypeScript/blob/master/CONTRIBUTING.md#contributing-libdts-fixes.