Update closure compiler to v20170124

package.json

@@ -32,7 +32,7 @@
   "dependencies": {
     "async": "2.1.4",
     "browserify": "13.1.1",
-    "closure-util": "1.16.0",
+    "closure-util": "1.17.0",
     "derequire": "2.0.6",
     "fs-extra": "1.0.0",
     "glob": "7.1.1",

tasks/build-ext.js

@@ -58,7 +58,7 @@ function wrapModule(mod, callback) {
         'constantProperty, deprecated, duplicate, es5Strict, ' +
         'fileoverviewTags, missingProperties, nonStandardJsDocs, ' +
         'strictModuleDepCheck, suspiciousCode, undefinedNames, ' +
-        'undefinedVars, unknownDefines, uselessCode, visibility}\n' +
+        'undefinedVars, unknownDefines, unusedLocalVariables, uselessCode, visibility}\n' +
         ' */\n' + code + '\n' +
         'ol.ext.' + mod.name + ' = module.exports;\n' +
         '})();\n';