importKey method
Implementation
Future<CryptoKey> importKey(KeyFormat format, dynamic keyData,
dynamic algorithm, bool extractable, Iterable<KeyUsage> keyUsages) =>
js_util.promiseToFuture(js_util.callMethod(this, 'importKey', [
format.value,
keyData,
algorithm,
extractable,
keyUsages.map((e) => e.value)
]));