Fix empty stack trace in assertion for platform typed expression

compiler/testData/codegen/boxWithStdlib/platformTypes/assertionStackTrace.kt

@@ -0,0 +1,21 @@
+import java.util.Arrays
+import java.util.ArrayList
+
+fun box(): String {
+    val a = ArrayList<String>()
+    a.add(null)
+    try {
+        val b: String = a[0]
+        return "Fail: an exception should be thrown"
+    } catch (e: IllegalStateException) {
+        val st = (e as java.lang.Throwable).getStackTrace()
+        if (st.size < 5) {
+            return "Fail: very small stack trace, should at least have current function and JUnit reflective calls: ${Arrays.toString(st)}"
+        }
+        val top = st[0]
+        if (!(top.getClassName().startsWith("_DefaultPackage") && top.getMethodName() == "box")) {
+            return "Fail: top stack trace element should be box() from default package, but was $top"
+        }
+        return "OK"
+    }
+}