Use sequence<T> instead of T[] where possible and document exceptions

third_party/WebKit/Source/modules/crypto/CryptoKey.idl

Index: third_party/WebKit/Source/modules/crypto/CryptoKey.idl
diff --git a/third_party/WebKit/Source/modules/crypto/CryptoKey.idl b/third_party/WebKit/Source/modules/crypto/CryptoKey.idl
index 9cd28dd316d7f2ef13a42228011893a4771b1a8c..bce2c9110d96f4bd23999e1a33c838cfe7de1eaf 100644
--- a/third_party/WebKit/Source/modules/crypto/CryptoKey.idl
+++ b/third_party/WebKit/Source/modules/crypto/CryptoKey.idl
@@ -28,11 +28,14 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+// https://w3c.github.io/webcrypto/Overview.html#cryptokey-interface
+
 [
     Exposed=(Window,Worker)
 ] interface CryptoKey {
     readonly attribute DOMString type;
     readonly attribute boolean extractable;
     [CallWith=ScriptState] readonly attribute object algorithm;
+    // TODO(jyasskin): |usages| should be of type object.
     readonly attribute DOMString[] usages;
 };