JS: move expressions test to box tests

js/js.translator/testData/box/dynamic/unaryOperations.kt

@@ -0,0 +1,20 @@
+package foo
+
+fun box(): String {
+    val a: dynamic = 12
+    var b: dynamic = 33.4
+    var c: dynamic = "text"
+    val d: dynamic = true
+
+    assertEquals(-12, -a)
+    assertEquals(33.4, +b)
+    testTrue { d }
+    testFalse { !d }
+    testTrue { !!d }
+    testFalse { !a }
+    testTrue { !!a }
+    testFalse { !b }
+    testTrue { !!b }
+
+    return "OK"
+}