JS: move more test to box tests

js/js.translator/testData/box/propertyAccess/setter.kt

@@ -0,0 +1,13 @@
+package foo
+
+class Test() {
+    var a: Int = 1
+}
+
+fun box(): String {
+    var b = Test()
+    assertEquals(1, b.a)
+    b.a = 100
+    assertEquals(100, b.a)
+    return "OK"
+}