JS: move expressions test to box tests

js/js.translator/testData/box/expression/misc/KT-817.kt

@@ -0,0 +1,21 @@
+package foo
+
+class Range() {
+
+    val reversed = false;
+    val start = 0;
+    var count = 10;
+
+    fun next() = start + if (reversed) -(--count) else (--count);
+}
+
+fun box(): String {
+    val r = Range()
+    if (r.next() != 9) {
+        return "fail1"
+    }
+    if (r.next() != 8) {
+        return "fail2"
+    }
+    return "OK"
+}