Add an alternate mechanism for registering default lints

pkg/analyzer/lib/src/lint/registry.dart

Index: pkg/analyzer/lib/src/lint/registry.dart
diff --git a/pkg/analyzer/lib/src/lint/registry.dart b/pkg/analyzer/lib/src/lint/registry.dart
index 20ce0367efcde1c8de0713ed4fbab4a15ec2d616..172767ba598e2f68d70fb65bc8c080cfab55045b 100644
--- a/pkg/analyzer/lib/src/lint/registry.dart
+++ b/pkg/analyzer/lib/src/lint/registry.dart
@@ -8,7 +8,7 @@ import 'package:analyzer/src/lint/config.dart';
 import 'package:analyzer/src/lint/linter.dart';
 
 /**
- * Registry of contributed lint rules.
+ * Registry of lint rules.
  */
 class Registry extends Object with IterableMixin<LintRule> {
   /**
@@ -16,27 +16,60 @@ class Registry extends Object with IterableMixin<LintRule> {
    */
   static final Registry ruleRegistry = new Registry();
 
+  /**
+   * A table mapping rule names to rules.
+   */
   Map<String, LintRule> _ruleMap = <String, LintRule>{};
 
+  /**
+   * A list of the default lint rules.
+   */
+  List<LintRule> _defaultRules = <LintRule>[];
+
+  /**
+   * Return a list of the default lint rules.
+   */
+  List<LintRule> get defaultRules => _defaultRules;
+
   @override
   Iterator<LintRule> get iterator => _ruleMap.values.iterator;
 
+  /**
+   * Return a list of the rules that are defined.
+   */
   Iterable<LintRule> get rules => _ruleMap.values;
 
-  LintRule operator [](String key) => _ruleMap[key];
+  /**
+   * Return the lint rule with the given [name].
+   */
+  LintRule operator [](String name) => _ruleMap[name];
 
-  /// All lint rules explicitly enabled by the given [config].
-  ///
-  /// For example:
-  ///     my_rule: true
-  ///
-  /// enables `my_rule`.
-  ///
-  /// Unspecified rules are treated as disabled by default.
+  /**
+   * Return a list of the lint rules explicitly enabled by the given [config].
+   *
+   * For example:
+   *     my_rule: true
+   *
+   * enables `my_rule`.
+   *
+   * Unspecified rules are treated as disabled by default.
+   */
   Iterable<LintRule> enabled(LintConfig config) => rules
       .where((rule) => config.ruleConfigs.any((rc) => rc.enables(rule.name)));
 
+  /**
+   * Add the given lint [rule] to this registry.
+   */
   void register(LintRule rule) {
     _ruleMap[rule.name] = rule;
   }
+
+  /**
+   * Add the given lint [rule] to this registry and mark it as being a default
+   * lint (one that will be run if lints are requested but no rules are enabled.
+   */
+  void registerDefault(LintRule rule) {
+    register(rule);
+    _defaultRules.add(rule);
+  }
 }