separate mocha node.js definition

mocha/mocha-node.d.ts

@@ -0,0 +1,16 @@
+// Type definitions for mocha 2.2.5
+// Project: http://mochajs.org/
+// Definitions by: Vadim Macagon <https://github.com/enlight>, vvakame <https://github.com/vvakame>
+// Definitions: https://github.com/borisyankov/DefinitelyTyped
+
+/// <reference path="mocha.d.ts" />
+/// <reference path="../node/node.d.ts" />
+
+declare module Mocha {
+    interface IRunnable extends NodeJS.EventEmitter {
+    }
+    interface ISuite extends NodeJS.EventEmitter {
+    }
+    interface IRunner extends NodeJS.EventEmitter {
+    }
+}