Hide aliases when printing 'pub --help'.

utils/pub/pub.dart

Index: utils/pub/pub.dart
diff --git a/utils/pub/pub.dart b/utils/pub/pub.dart
index df40c064e4e92954fbf3e83c9b3ad327dd12aaa1..9bb12ee39ae268de0dd126c1d1ad6a48f755dee9 100644
--- a/utils/pub/pub.dart
+++ b/utils/pub/pub.dart
@@ -134,6 +134,8 @@ void printUsage([String description = 'Pub is a package manager for Dart.']) {
   int length = 0;
   var names = <String>[];
   for (var command in pubCommands.keys) {
+    // Hide aliases.
+    if (pubCommands[command].aliases.indexOf(command) >= 0) continue;
     length = max(length, command.length);
     names.add(command);
   }