THRIFT-4604: NodeJS add Int64 to exports for browserify (#1573)

diff --git a/lib/nodejs/lib/thrift/browser.js b/lib/nodejs/lib/thrift/browser.js
index 4593a8f..67ce853 100644
--- a/lib/nodejs/lib/thrift/browser.js
+++ b/lib/nodejs/lib/thrift/browser.js
@@ -32,3 +32,5 @@
 exports.Protocol = exports.TJSONProtocol = require('./json_protocol');
 exports.TBinaryProtocol = require('./binary_protocol');
 exports.TCompactProtocol = require('./compact_protocol');
+
+exports.Int64 = require('node-int64');