Make a bunch of stuff in pub synchronous.

utils/pub/validator/dependency.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dependency_validator;
 
 import 'dart:async';
 
 import '../entrypoint.dart';
 import '../hosted_source.dart';
@@ skipping 20 matching lines @@
             'Pub enables "package:${entrypoint.root.name}" imports '
                 'implicitly.');
         return new Future.immediate(null);
       }
 
       if (dependency.constraint.isAny &&
           // TODO(nweiz): once we have development dependencies (issue 5358), we
           // should warn about unittest. Until then, it's reasonable not to put
           // a constraint on it.
           dependency.name != 'unittest') {
-        return _warnAboutConstraint(dependency);
+        _warnAboutConstraint(dependency);
       }
 
       return new Future.immediate(null);
     });
   }
 
   /// Warn that dependencies should use the hosted source.
   Future _warnAboutSource(PackageRef ref) {
     return entrypoint.cache.sources['hosted']
         .getVersions(ref.name, ref.name)
@@ skipping 15 matching lines @@
           '\n'
           'dependencies:\n'
           '  ${ref.name}: $constraint\n'
           '\n'
           'Using the hosted source ensures that everyone can download your '
               'package\'s dependencies along with your package.');
     });
   }
 
   /// Warn that dependencies should have version constraints.
-  Future _warnAboutConstraint(PackageRef ref) {
-    return entrypoint.loadLockFile().then((lockFile) {
-      var message = 'Your dependency on "${ref.name}" should have a version '
-          'constraint.';
-      var locked = lockFile.packages[ref.name];
-      if (locked != null) {
-        message = '$message For example:\n'
-          '\n'
-          'dependencies:\n'
-          '  ${ref.name}: ${_constraintForVersion(locked.version)}\n';
-      }
-      warnings.add("$message\n"
-          "Without a constraint, you're promising to support all future "
-          "versions of ${ref.name}.");
-    });
+  void _warnAboutConstraint(PackageRef ref) {
+    var lockFile = entrypoint.loadLockFile();
+    var message = 'Your dependency on "${ref.name}" should have a version '
+        'constraint.';
+    var locked = lockFile.packages[ref.name];
+    if (locked != null) {
+      message = '$message For example:\n'
+        '\n'
+        'dependencies:\n'
+        '  ${ref.name}: ${_constraintForVersion(locked.version)}\n';
+    }
+    warnings.add("$message\n"
+        "Without a constraint, you're promising to support all future "
+        "versions of ${ref.name}.");
   }
 
   /// Returns the suggested version constraint for a dependency that was tested
   /// against [version].
   String _constraintForVersion(Version version) {
     if (version.major != 0) return '">=$version <${version.major + 1}.0.0"';
     return '">=$version <${version.major}.${version.minor}.'
         '${version.patch + 1}"';
   }
 }