Fix scala-js#384: Make locales optional in DateTimeFormat & NumberFormat. (scala-js#385)

Author: TATSUNO Yasuhiro

src/main/scala/org/scalajs/dom/experimental/intl/Intl.scala

@@ -35,7 +35,8 @@ class Collator(locales: js.UndefOr[String | js.Array[String]] = js.undefined,
  */
 @js.native
 @JSGlobal("Intl.DateTimeFormat")
-class DateTimeFormat(locales: String | js.Array[String],
+class DateTimeFormat(
+ locales: js.UndefOr[String | js.Array[String]] = js.undefined,
  options: js.UndefOr[DateTimeFormatOptions] = js.undefined)
  extends js.Object {
  def format(date: js.Date): String = js.native
@@ -52,8 +53,9 @@ class DateTimeFormat(locales: String | js.Array[String],
  */
 @js.native
 @JSGlobal("Intl.NumberFormat")
-class NumberFormat(locales: String | js.Array[String],
- options: js.UndefOr[NumberFormatOptions])
+class NumberFormat(
+ locales: js.UndefOr[String | js.Array[String]] = js.undefined,
+ options: js.UndefOr[NumberFormatOptions] = js.undefined)
  extends js.Object {
  def format(number: Double): String = js.native
  def resolvedOptions(): NumberFormatOptions = js.native