update closure compiler

build/Gruntfile.js

@@ -162,6 +162,7 @@ module.exports = function(grunt) {
 		var sdkAllDst = sdkDstFolder + '/sdk-all.js';
 		var sdkAllCache = sdkDstFolder + '/*.cache'
 		var sdkOpt = {
+			jscomp_off: 'externsValidation',
 			compilation_level: level,
 			warning_level: 'QUIET',
 			externs: packageFile['compile']['sdk']['externs']

build/package.json

@@ -4,7 +4,7 @@
   "homepage": "http://www.onlyoffice.com",
   "private": true,
   "dependencies": {
-    "google-closure-compiler": "20170218.0.0",
+    "google-closure-compiler": "20170423.0.0",
     "grunt": "1.0.1",
 	"grunt-contrib-clean": "1.0.0",
     "grunt-contrib-concat": "1.0.1",