Fix the JS demo compilation with the latest Closure compiler (#2592)

* strictMissingRequire is not supported by recent Closure compiler

* JS: Explicitly require goog.proto2.Descriptor

javascript/build.xml

@@ -47,7 +47,7 @@
         <arg line='-f "--jscomp_error=misplacedTypeAnnotation"' />
         <arg line='-f "--jscomp_error=missingProperties"' />
         <arg line='-f "--jscomp_error=missingRequire"' />
-        <arg line='-f "--jscomp_error=strictMissingRequire"' />
+        <arg line='-f "--jscomp_error=missingRequire"' />
         <arg line='-f "--jscomp_error=nonStandardJsDocs"' />
         <arg line='-f "--jscomp_error=strictModuleDepCheck"' />
         <arg line='-f "--jscomp_error=suspiciousCode"' />

javascript/i18n/phonenumbers/phonemetadata.pb.js

@@ -27,6 +27,7 @@ goog.provide('i18n.phonenumbers.PhoneMetadata');
 goog.provide('i18n.phonenumbers.PhoneMetadataCollection');
 
 goog.require('goog.proto2.Message');
+goog.require('goog.proto2.Descriptor');
 
 
 

javascript/i18n/phonenumbers/phonenumber.pb.js

@@ -26,6 +26,7 @@ goog.provide('i18n.phonenumbers.PhoneNumber');
 goog.provide('i18n.phonenumbers.PhoneNumber.CountryCodeSource');
 
 goog.require('goog.proto2.Message');
+goog.require('goog.proto2.Descriptor');