JS: move more test to box tests

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

@@ -0,0 +1,21 @@
+package foo
+
+interface Test {
+    fun addFoo(s: String): String {
+        return s + "FOO"
+    }
+}
+
+interface ExtendedTest : Test {
+    fun hooray(): String {
+        return "hooray"
+    }
+}
+
+class A() : ExtendedTest {
+    fun eval(): String {
+        return addFoo(hooray());
+    }
+}
+
+fun box() = if (A().eval() == "hoorayFOO") "OK" else "fail"