JS: move more test to box tests

js/js.translator/testData/box/safeCall/safeCall.kt

@@ -0,0 +1,12 @@
+package foo
+
+class A() {
+    fun doSomething() {
+    }
+}
+
+fun box(): String {
+    var a: A? = null;
+    a?.doSomething()
+    return "OK"
+}