JS: move expressions test to box tests

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

@@ -0,0 +1,14 @@
+package foo
+
+
+fun box(): String {
+    var result = "fail1"
+    var i = 1
+    loop@ while(i==1)
+        when (i) {
+            1 -> { result = "OK"; break@loop }
+            else -> result = "fail"
+        }
+    return result
+}
+