JS: move expressions test to box tests

js/js.translator/testData/box/expression/stringClass/intInTemplate.kt

@@ -0,0 +1,10 @@
+// CHECK_NOT_CALLED_IN_SCOPE: scope=box function=toString
+
+package foo
+
+fun box(): String {
+    var number = 3
+    assertEquals("my age is 3", "my age is $number")
+    return "OK"
+}
+