tests: Copy stdlib tests from Kotlin/JVM

This patch copies Kotlin/JVM stdlib tests (libraries/stdlib/test)
excepting ones with explicit java dependencies. It also transforms
the tests to use them as box-tests.

backend.native/tests/external/stdlib/collections/CollectionTest/abstractCollectionToArray.kt

@@ -0,0 +1,30 @@
+import kotlin.test.*
+import kotlin.comparisons.*
+
+fun box() {
+    class TestCollection<out E>(val data: Collection<E>) : AbstractCollection<E>() {
+        val invocations = mutableListOf<String>()
+        override val size get() = data.size
+        override fun iterator() = data.iterator()
+
+        override fun toArray(): Array<Any?> {
+            invocations += "toArray1"
+            return data.toTypedArray()
+        }
+
+        public override fun <T> toArray(array: Array<T>): Array<T> {
+            invocations += "toArray2"
+            return super.toArray(array)
+        }
+    }
+
+    val data = listOf("abc", "def")
+    val coll = TestCollection(data)
+
+    val arr1 = coll.toTypedArray()
+    assertEquals(data, arr1.asList())
+    assertTrue("toArray1" in coll.invocations || "toArray2" in coll.invocations)
+
+    val arr2: Array<String> = coll.toArray(Array(coll.size + 1) { "" })
+    assertEquals(data + listOf(null), arr2.asList())
+}