JS stdlib: drop TuplesCode.kt -- switch to use tuples from stdlib.

js/js.libraries/src/core/javaio.kt

@@ -7,3 +7,5 @@ library
 public trait Closeable {
     public open fun close() : Unit;
 }
+
+trait Serializable

js/js.libraries/src/stdlib/TuplesCode.kt

@@ -1,24 +0,0 @@
-package kotlin
-
-// TODO: make it a data class
-public class Pair<A, B> (
-        public val first: A,
-        public val second: B
-) {
-    public fun component1(): A = first
-    public fun component2(): B = second
-
-    override fun toString(): String = "($first, $second)"
-}
-
-public class Triple<A, B, C> (
-        public val first: A,
-        public val second: B,
-        public val third: C
-) {
-    public fun component1(): A = first
-    public fun component2(): B = second
-    public fun component3(): C = third
-
-    override fun toString(): String = "($first, $second, $third)"
-}