Minor: refactor some tests to use nested classes.

libraries/stdlib/test/collections/CollectionTest.kt

@@ -1,3 +1,19 @@
+/*
+ * Copyright 2010-2016 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package test.collections
 
 import java.util.*
@@ -594,7 +610,7 @@ class CollectionTest {
         assertFalse(hashSetOf<Int>().contains(12))
         assertTrue(listOf(15, 19, 20).contains(15))
 
-        assertTrue(IterableWrapper(hashSetOf(45, 14, 13)).contains(14))
+        assertTrue(hashSetOf(45, 14, 13).toIterable().contains(14))
     }
 
     @test fun min() {