Fix use of chain in intl library.

pkg/intl/lib/intl_standalone.dart

Index: pkg/intl/lib/intl_standalone.dart
diff --git a/pkg/intl/lib/intl_standalone.dart b/pkg/intl/lib/intl_standalone.dart
index cf2e4ef4f10c4e56652b8df4f7e545eb95552788..cce7722eead2d850eb85bba473e682789d92e7ba 100644
--- a/pkg/intl/lib/intl_standalone.dart
+++ b/pkg/intl/lib/intl_standalone.dart
@@ -81,7 +81,7 @@ String _checkEnvironmentVariable() {
  */
 Future _getAppleDefaults() {
   var p = Process.run('defaults', ['read', '-g', 'AppleLocale']);
-  var myResult = p.chain((result) => _checkResult(result, _appleDefaultsRegex));
+  var myResult = p.then((result) => _checkResult(result, _appleDefaultsRegex));
   return myResult;
 }
 
@@ -90,7 +90,7 @@ Future _getAppleDefaults() {
  */
 Future _getWindowsSystemInfo() {
   var p = Process.run('systeminfo', []);
-  var myResult = p.chain((result) => _checkResult(result, _sysInfoRegex));
+  var myResult = p.then((result) => _checkResult(result, _sysInfoRegex));
   return myResult;
 }