Move Closeable to its usage, move internal Serializable to kotlin package in JS, introduce internal typealias in kotlin.io in JVM.

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

@@ -1,8 +0,0 @@
-package java.io
-
-@library
-public interface Closeable {
-    public fun close(): Unit
-}
-
-internal interface Serializable

js/js.libraries/src/core/kotlin.kt

@@ -101,4 +101,7 @@ internal inline fun <T> Array<out T>.copyToArrayOfAny(isVarargs: Boolean): Array
             // no need to copy vararg array in JS
             this
         else
-            this.copyOf()
+            this.copyOf()
+
+// temporary for shared code, until we have an annotation like JvmSerializable
+internal interface Serializable

js/js.libraries/src/dom/DomEvents.kt

@@ -1,6 +1,5 @@
 package kotlin.dom
 
-import java.io.Closeable
 import org.w3c.dom.*
 import org.w3c.dom.events.*
 
@@ -26,6 +25,10 @@ public fun mouseEventHandler(handler: (MouseEvent) -> Unit): EventListener {
     }
 }
 
+public interface Closeable {
+    public open fun close(): Unit
+}
+
 /**
  * Registers a handler on the named event
  */