JS: move expressions test to box tests

js/js.translator/testData/box/expression/function/defaultParameters.kt

@@ -0,0 +1,13 @@
+package foo
+
+fun f(a: Int = 2, b: Int = 3) = a + b
+
+fun box(): String {
+    if (f(1, 2) != 3) return "fail1"
+    if (f(1, 3) != 4) return "fail2"
+    if (f(3) != 6) return "fail3"
+    if (f() != 5) return "fail4"
+
+    return "OK"
+}
+