Temporary drop mapNotNull and mapNotNullTo.

Disable mapNotNull tests

#KT-4410

libraries/stdlib/test/collections/CollectionTest.kt

@@ -36,6 +36,7 @@ class CollectionTest {
         }
     }
 
+    /*
     @test fun mapNotNull() {
         val data = listOf(null, "foo", null, "bar")
         val foo = data.mapNotNull { it.length() }
@@ -46,6 +47,7 @@ class CollectionTest {
             foo is List<Int>
         }
     }
+    */
 
     @test fun listOfNotNull() {
         val l1: List<Int> = listOfNotNull(null)

libraries/stdlib/test/collections/SequenceTest.kt

@@ -63,6 +63,7 @@ public class SequenceTest {
         assertEquals(listOf("foo", "bar"), filtered.toList())
     }
 
+    /*
     @test fun mapNotNull() {
         val data = sequenceOf(null, "foo", null, "bar")
         val foo = data.mapNotNull { it.length() }
@@ -72,6 +73,7 @@ public class SequenceTest {
             foo is Sequence<Int>
         }
     }
+    */
 
     @test fun mapIndexed() {
         assertEquals(listOf(0, 1, 2, 6, 12), fibonacci().mapIndexed { index, value -> index * value }.takeWhile { i: Int -> i < 20 }.toList())