JS: create new common directory for all generated tests, migrate several tests there

js/js.translator/testData/box/inheritance/methodOverride.kt

@@ -0,0 +1,27 @@
+package foo
+
+open class A {
+    fun f1(): Int {
+        return 1
+    }
+    open fun f2(): Int {
+        return 3
+    }
+}
+
+class B : A() {
+    override fun f2(): Int {
+        return 2
+    }
+}
+
+fun box(): String {
+    val a = A()
+    if (a.f1() != 1) return "a.f1() != 1, it: ${a.f1()}"
+    if (a.f2() != 3) return "a.f2() != 3, it: ${a.f2()}"
+
+    val b = B();
+    if (b.f1() != 1) return "b.f1() != 1, it: ${b.f1()}"
+    if (b.f2() != 2) return "b.f2() != 2, it: ${b.f2()}"
+    return "OK"
+}