Introduce RandomAccess to JS.

Make EmptyList support RandomAccess.
#KT-10794

js/js.libraries/src/core/javautil.kt

@@ -31,6 +31,9 @@ public inline fun <T> Comparator(crossinline comparison: (T, T) -> Int): Compara
     override fun compare(obj1: T, obj2: T): Int = comparison(obj1, obj2)
 }
 
+@library
+public interface RandomAccess
+
 @library
 public abstract class AbstractCollection<E>() : MutableCollection<E> {
     override fun isEmpty(): Boolean = noImpl
@@ -79,7 +82,7 @@ public abstract class AbstractList<E>() : AbstractCollection<E>(), MutableList<E
 }
 
 @library
-public open class ArrayList<E>(capacity: Int = 0) : AbstractList<E>() {
+public open class ArrayList<E>(capacity: Int = 0) : AbstractList<E>(), RandomAccess {
     override fun get(index: Int): E = noImpl
     override val size: Int get() = noImpl
 }

js/js.translator/testData/kotlin_lib.js

@@ -350,6 +350,8 @@
         }
     );
 
+    Kotlin.RandomAccess = Kotlin.createTraitNow(null);
+
     Kotlin.PropertyMetadata = Kotlin.createClassNow(null,
         function (name) {
             this.name = name;
@@ -566,7 +568,7 @@
     //TODO: should be JS Array-like (https://developer.mozilla.org/en-US/docs/JavaScript/Guide/Predefined_Core_Objects#Working_with_Array-like_objects)
     lazyInitClasses.ArrayList = Kotlin.createClass(
         function () {
-            return [Kotlin.AbstractList];
+            return [Kotlin.AbstractList, Kotlin.RandomAccess];
         },
         function () {
             this.array = [];

libraries/stdlib/src/kotlin/collections/Collections.kt

@@ -16,7 +16,7 @@ internal object EmptyIterator : ListIterator<Nothing> {
     override fun previous(): Nothing = throw NoSuchElementException()
 }
 
-internal object EmptyList : List<Nothing>, Serializable {
+internal object EmptyList : List<Nothing>, Serializable, RandomAccess {
     override fun equals(other: Any?): Boolean = other is List<*> && other.isEmpty()
     override fun hashCode(): Int = 1
     override fun toString(): String = "[]"

libraries/stdlib/test/collections/CollectionTest.kt

@@ -854,4 +854,11 @@ class CollectionTest {
         // we need toString() inside pattern because of KT-8666
         assertEquals("[1, a, null, ${Long.MAX_VALUE.toString()}]", listOf(1, "a", null, Long.MAX_VALUE).toString())
     }
+
+    @test fun randomAccess() {
+        assertTrue(arrayListOf(1) is RandomAccess, "ArrayList is RandomAccess")
+        assertTrue(listOf(1, 2) is RandomAccess, "Default read-only list implementation is RandomAccess")
+        assertTrue(listOf(1) is RandomAccess, "Default singleton list is RandomAccess")
+        assertTrue(emptyList<Int>() is RandomAccess, "Empty list is RandomAccess")
+    }
 }