Added test to check fields deserialization from caches (#4540)

kotlin-native/backend.native/tests/serialization/deserialized_fields.kt

@@ -0,0 +1,16 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+package serialization.deserialized_fields
+
+import kotlin.test.*
+
+class CustomThrowable(val extraInfo: String): Throwable("Some message", null)
+
+@Test fun runTest() {
+    val custom = CustomThrowable("Extra info")
+    assertEquals(custom.extraInfo, "Extra info")
+    assertEquals(custom.message, "Some message")
+    assertEquals(custom.cause, null)
+}