[FIR] Fix TEST SPEC tests

Ensure the test data contents for both the frontends
are identical. This is needed for proper analysis of
K2-differences.

compiler/tests-spec/testData/diagnostics/notLinked/dfa/pos/5.fir.kt

@@ -1,6 +1,15 @@
 // !DIAGNOSTICS: -UNUSED_EXPRESSION
 // SKIP_TXT
 
+/*
+ * KOTLIN DIAGNOSTICS NOT LINKED SPEC TEST (POSITIVE)
+ *
+ * SECTIONS: dfa
+ * NUMBER: 5
+ * DESCRIPTION: Raw data flow analysis test
+ * HELPERS: classes, interfaces, properties, functions
+ */
+
 // TESTCASE NUMBER: 1
 fun case_1(x: Any?) {
     if (x is Number?) {