Cleanup: use effects introduced by contracts of assert* functions

libraries/kotlin.test/jvm/src/test/kotlin/TestJVMTest.kt

@@ -30,14 +30,14 @@ class TestJVMTest {
     @Test
     fun assertEqualsMessage() {
         expectAssertion({ msg ->
-                            assertNotNull(msg); msg!!
+                            assertNotNull(msg)
                             assertTrue { msg.contains(expected.toString()) }
                             assertTrue { msg.contains(actual.toString()) }
                             assertFalse { msg.startsWith(".") }
                         }, { assertEquals<Any>(expected, actual) })
 
         expectAssertion({ msg ->
-                            assertNotNull(msg); msg!!
+                            assertNotNull(msg)
                             assertTrue { msg.contains(message) }
                             assertTrue { msg.contains(expected.toString()) }
                             assertTrue { msg.contains(actual.toString()) }
@@ -47,13 +47,13 @@ class TestJVMTest {
     @Test
     fun assertNotEqualsMessage() {
         expectAssertion({ msg ->
-                            assertNotNull(msg); msg!!
+                            assertNotNull(msg)
                             assertTrue { msg.contains(actual.toString()) }
                             assertFalse { msg.startsWith(".") }
                         }, { assertNotEquals(actual, actual) })
 
         expectAssertion({ msg ->
-                            assertNotNull(msg); msg!!
+                            assertNotNull(msg)
                             assertTrue { msg.contains(message) }
                             assertTrue { msg.contains(actual.toString()) }
                         }, { assertNotEquals(actual, actual, message) })

libraries/stdlib/test/text/RegexTest.kt

@@ -32,7 +32,7 @@ class RegexTest {
         assertTrue(p in input)
 
         val first = p.find(input)
-        assertTrue(first != null); first!!
+        assertNotNull(first)
         assertEquals("123", first.value)
 
         val second1 = first.next()!!