Kotlinc 2.4 language version update pre-work.

Fix impossible is checks that are guaranteed to always returns false.

PiperOrigin-RevId: 958436856

java/kotlin/src/test/kotlin/com/google/protobuf/DslListTest.kt

@@ -36,7 +36,7 @@ class DslListTest {
   @Test
   fun dslListIsNotMutable() {
     val dslList = DslList<Int, DummyProxy>(mutableListOf(1, 2, 3))
-    assertThat(dslList is MutableList<*>).isFalse()
+    assertThat((dslList as Any) is MutableList<*>).isFalse()
   }
 
   @Suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN", "UNCHECKED_CAST")

java/kotlin/src/test/kotlin/com/google/protobuf/DslMapTest.kt

@@ -35,7 +35,7 @@ class DslMapTest {
   @Test
   fun dslMapIsNotMutable() {
     val dslMap = DslMap<Int, Int, DummyProxy>(mutableMapOf(1 to -1))
-    assertThat(dslMap is MutableMap<*, *>).isFalse()
+    assertThat((dslMap as Any) is MutableMap<*, *>).isFalse()
   }
 
   @Test

java/kotlin/src/test/kotlin/com/google/protobuf/ExtensionListTest.kt

@@ -47,7 +47,7 @@ class ExtensionListTest {
         TestProto.repeatedExtension,
         mutableListOf(1, 2, 3),
       )
-    assertThat(extensionList is MutableList<*>).isFalse()
+    assertThat((extensionList as Any) is MutableList<*>).isFalse()
   }
 
   @Suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN", "UNCHECKED_CAST")