Update doc comments to follow style guide.

sdk/lib/_internal/pub/lib/src/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 pub.validator.dependency;
 
 import 'dart:async';
 
 import '../entrypoint.dart';
 import '../log.dart' as log;
@@ skipping 72 matching lines @@
       message = '$message For example:\n'
         '\n'
         'dependencies:\n'
         '  ${dep.name}: ${_constraintForVersion(locked.version)}\n';
     }
     warnings.add("$message\n"
         'Without a constraint, you\'re promising to support ${log.bold("all")} '
             'future versions of "${dep.name}".');
   }
 
-  // Warn that dependencies should allow more than a single version.
+  /// Warn that dependencies should allow more than a single version.
   void _warnAboutSingleVersionConstraint(PackageDep dep) {
     warnings.add(
         'Your dependency on "${dep.name}" should allow more than one version. '
             'For example:\n'
         '\n'
         'dependencies:\n'
         '  ${dep.name}: ${_constraintForVersion(dep.constraint)}\n'
         '\n'
         'Constraints that are too tight will make it difficult for people to '
             'use your package\n'
         'along with other packages that also depend on "${dep.name}".');
   }
 
-  // Warn that dependencies should have lower bounds on their constraints.
+  /// Warn that dependencies should have lower bounds on their constraints.
   void _warnAboutNoConstraintLowerBound(PackageDep dep) {
     var message = 'Your dependency on "${dep.name}" should have a lower bound.';
     var locked = entrypoint.loadLockFile().packages[dep.name];
     if (locked != null) {
       var constraint;
       if (locked.version == (dep.constraint as VersionRange).max) {
         constraint = _constraintForVersion(locked.version);
       } else {
         constraint = '">=${locked.version} ${dep.constraint}"';
       }
 
       message = '$message For example:\n'
         '\n'
         'dependencies:\n'
         '  ${dep.name}: $constraint\n';
     }
     warnings.add("$message\n"
         'Without a constraint, you\'re promising to support ${log.bold("all")} '
             'previous versions of "${dep.name}".');
   }
 
-  // Warn that dependencies should have upper bounds on their constraints.
+  /// Warn that dependencies should have upper bounds on their constraints.
   void _warnAboutNoConstraintUpperBound(PackageDep dep) {
     warnings.add(
         'Your dependency on "${dep.name}" should have an upper bound. For '
             'example:\n'
         '\n'
         'dependencies:\n'
         '  ${dep.name}: "${dep.constraint} '
             '${_upperBoundForVersion((dep.constraint as VersionRange).min)}"\n'
         '\n'
         'Without an upper bound, you\'re promising to support '
             '${log.bold("all")} future versions of ${dep.name}.');
   }
 
   /// Returns the suggested version constraint for a dependency that was tested
   /// against [version].
   String _constraintForVersion(Version version) =>
       '">=$version ${_upperBoundForVersion(version)}"';
 
   /// Returns the suggested upper bound for a dependency that was tested against
   /// [version].
   String _upperBoundForVersion(Version version) {
     if (version.major != 0) return '<${version.major + 1}.0.0';
     return '<${version.major}.${version.minor + 1}.0';
   }
 }