[Wasm] Move ItemArrayLike w3c declarations into the right package

libraries/stdlib/wasm/src/kotlin/w3cSupport.kt

@@ -12,18 +12,4 @@ internal val undefined: Nothing? = null
  * Exposes the JavaScript [eval function](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/eval) to Kotlin.
  */
 @JsFun("(s) => eval(s)")
-external fun js(code: String): Dynamic
-
-external interface ItemArrayLike<out T> {
-    val length: Int
-    fun item(index: Int): T?
-}
-
-fun <T> ItemArrayLike<T>.asList(): List<T> = object : AbstractList<T>() {
-    override val size: Int get() = this@asList.length
-
-    override fun get(index: Int): T = when (index) {
-        in 0..lastIndex -> this@asList.item(index) as T
-        else -> throw IndexOutOfBoundsException("index $index is not in range [0..$lastIndex]")
-    }
-}
+external fun js(code: String): Dynamic

libraries/stdlib/wasm/src/kotlinx/dom/ItemArrayLike.kt

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2010-2022 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.w3c.dom
+
+public external interface ItemArrayLike<out T> {
+    val length: Int
+    fun item(index: Int): T?
+}
+
+public fun <T> ItemArrayLike<T>.asList(): List<T> = object : AbstractList<T>() {
+    override val size: Int get() = this@asList.length
+
+    override fun get(index: Int): T = when (index) {
+        in 0..lastIndex -> this@asList.item(index) as T
+        else -> throw IndexOutOfBoundsException("index $index is not in range [0..$lastIndex]")
+    }
+}