JS lib: export Kotlin object when it possible.

It allows use kotlin.js on node.js without modifications.

js/js.translator/testData/export_Kotlin_if_possible.js

@@ -0,0 +1,3 @@
+if (typeof module !== 'undefined' && module.exports) {
+    module.exports = Kotlin;
+}

js/js.translator/testData/externs.js

@@ -18,3 +18,10 @@
 
 // from QUnit
 function ok() {}
+
+// node.js
+var module = {};
+var process = {};
+
+// common
+var console = {};