How do I represent the boxed Double in pure Scala?

In Scala there are 2 representations of double-precision numbers, one is an AnyVal, the other AnyRef. On the JVM they are mapped to the primitive double and the class java.lang.Double respectively.

Now what happens on platforms other than the JVM? I can use Scala.Double for the primitive, but how do I specify that I want a reference to the boxed Double without specifying java.lang.Double?

[Context - left to make sense of Thomasz' answer, but not the fundamental issue.

I have a Double that I want to inject with Spring into a Wicket component:

class MyPanel(id: String) extends Panel(id) {
  @SpringBean(name="rxAlarmLimitDb") var alarmLimitDb: Double = _

If I specify the type as scala.Double as above, the injector fails, as it can only inject Objects.

If I specify java.lang.Double as the type of the field, all is well

class MyPanel(id: String) extends Panel(id) {
  @SpringBean(name="rxAlarmLimitDb") var alarmLimitDb: java.lang.Double = _

But I'm trying to reduce my dependance on falling back on the Java API, so how do I represent the boxed Double without it? ]