Add offline support to pub install and update.

sdk/lib/_internal/pub/lib/src/command_lish.dart

Index: sdk/lib/_internal/pub/lib/src/command_lish.dart
diff --git a/sdk/lib/_internal/pub/lib/src/command_lish.dart b/sdk/lib/_internal/pub/lib/src/command_lish.dart
index cc0311862dbcf40c452e09c7b2e042ed4277ed40..44a13ae1c3167562b0baab9817fe101b8f062c66 100644
--- a/sdk/lib/_internal/pub/lib/src/command_lish.dart
+++ b/sdk/lib/_internal/pub/lib/src/command_lish.dart
@@ -35,11 +35,11 @@ class LishCommand extends PubCommand {
     // TODO(nweiz): Use HostedSource.defaultUrl as the default value once we use
     // dart:io for HTTPS requests.
     parser.addFlag('dry-run', abbr: 'n', negatable: false,
-        help: 'Validate but do not publish the package');
+        help: 'Validate but do not publish the package.');
     parser.addFlag('force', abbr: 'f', negatable: false,
-        help: 'Publish without confirmation if there are no errors');
+        help: 'Publish without confirmation if there are no errors.');
     parser.addOption('server', defaultsTo: 'https://pub.dartlang.org',
-        help: 'The package server to which to upload this package');
+        help: 'The package server to which to upload this package.');
     return parser;
   }