Add various tests for DFA testing

compiler/tests-spec/testData/diagnostics/notLinked/dfa/neg/10.kt

@@ -0,0 +1,26 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+// SKIP_TXT
+
+/*
+ * KOTLIN DIAGNOSTICS NOT LINKED SPEC TEST (NEGATIVE)
+ *
+ * SECTIONS: dfa
+ * NUMBER: 10
+ * DESCRIPTION: Raw data flow analysis test
+ * HELPERS: classes, objects, typealiases, enumClasses, interfaces, sealedClasses
+ */
+
+// TESTCASE NUMBER: 1
+fun case_1() {
+    var x: Any? = <!VARIABLE_WITH_REDUNDANT_INITIALIZER!>null<!>
+
+    if (true) {
+        x = ClassLevel2()
+    } else {
+        x = ClassLevel3()
+    }
+
+    <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Any & kotlin.Any?")!>x<!>
+    <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Any & kotlin.Any?")!>x<!>.<!DEBUG_INFO_UNRESOLVED_WITH_TARGET, UNRESOLVED_REFERENCE_WRONG_RECEIVER!>inv<!>()
+}