Move blackBoxFile() testData to box/ directory

Delete all test methods (and empty test classes), since they'll be
auto-generated

compiler/testData/codegen/box/classes/kt1439.kt

@@ -0,0 +1,17 @@
+class MyClass(var fnc : () -> String) {
+
+    fun test(): String {
+        return fnc()
+    }
+
+}
+
+fun printtest() : String {
+    return "OK"
+}
+
+fun box(): String {
+    var c = MyClass({ printtest() })
+
+    return c.test()
+}