Generated default implementations for Collection.toArray().

#KT-3352 in progress

compiler/testData/codegen/box/toArray/toArray.kt

@@ -0,0 +1,21 @@
+import java.util.Arrays
+
+class MyCollection<T>(val delegate: Collection<T>): Collection<T> by delegate
+
+fun box(): String {
+    val collection = MyCollection(Arrays.asList(2, 3, 9)) as java.util.Collection<*>
+
+    val array1 = collection.toArray()
+    val array2 = collection.toArray(Array<Int>(3, { 0 }))
+
+    if (array1 !is Array<Any>) return (array1 as Object).getClass().toString()
+    if (array2 !is Array<Int>) return (array2 as Object).getClass().toString()
+
+    val s1 = Arrays.toString(array1)
+    val s2 = Arrays.toString(array2)
+
+    if (s1 != "[2, 3, 9]") return "s1 = $s1"
+    if (s2 != "[2, 3, 9]") return "s2 = $s2"
+
+    return "OK"
+}