Behaviour of is operator on Int and Double

[flonso]

The following Kotlin code doesn't produce the same output on both Kotlin "stock" compiler and the Kotlin-Scala.js compiler :

fun main(args: Array<String>) {
    val myDouble = 1.7

    check(myDouble)
}

fun check(a: Any) {

    if (a is Int) println("$a is an Int")
    if (a is Double) println("$a is a Double")
    if (a is Long) println("$a is a Long")


    if (a !is Int) println("$a is not an Int")
    if (a !is Double) println("$a is not a Double")
    if (a !is Long) println("$a is not a Long")
}

Output for KotlinJS compiler :

1.7 is an Int
1.7 is a Double
1.7 is not a Long

Output for Kotlin-Scala.js compiler :

1.7 is a Double
1.7 is not an Int
1.7 is not a Long

Need to investigate the reason behind this difference.