JS: move more test to box tests

js/js.translator/testData/box/trait/traitAddsFunctionsToClass.kt

@@ -0,0 +1,21 @@
+package foo
+
+interface Test {
+    fun addFoo(s: String): String {
+        return s + "FOO"
+    }
+
+    fun addBar(s: String): String {
+        return s + "BAR"
+    }
+}
+
+
+class A() : Test {
+    val string = "TEST"
+    fun value(): String {
+        return addBar(addFoo(string))
+    }
+}
+
+fun box() = if (A().value() == "TESTFOOBAR") "OK" else "fail"