Added correctness check of test data + fixed huge amount of incorrect code in test data

idea/testData/slicer/outflow/overridingFunctionResultWithJava.kt

@@ -1,10 +1,10 @@
 // FLOW: OUT
 
-open class B : A() {
+internal open class B : A() {
     override fun foo() = <caret>2
 }
 
-fun test(a: A, b: B, c: C) {
+internal fun test(a: A, b: B, c: C) {
     val x = a.foo()
     val y = b.foo()
     val z = c.foo()