JS: move expressions test to box tests

js/js.translator/testData/box/expression/when/ifInWhen.kt

@@ -0,0 +1,24 @@
+// KT-2221 if in when
+
+package foo
+
+fun test(caseId: Int, value: Int, expected: Int) {
+    val actual: Int
+    when (caseId) {
+        0 -> if (value < 0) actual = -value else actual = value
+        1 -> actual = if (value < 0) -value else value
+        else -> throw Exception("Unexpected case: $caseId")
+    }
+
+    if (expected != actual) throw Exception("expected = $expected, actual = $actual")
+}
+
+fun box(): String {
+    test(0, 3, 3)
+    test(0, -13, 13)
+    test(1, 23, 23)
+    test(1, -3, 3)
+
+    return "OK"
+}
+