feat(dart/analysis): Build DirectiveMetadata for LibrarySpecificUnit

initial commit for the dart analyzer task

modules_dart/analyzer_plugin/lib/plugin.dart

@@ -0,0 +1,25 @@
+library angular2.src.analysis.analyzer_plugin;
+
+import 'package:analyzer/plugin/plugin.dart';
+import 'package:analyzer/plugin/task.dart';
+import 'src/tasks.dart';
+
+/// Contribute a plugin to the dart analyzer for analysis of
+/// Angular 2 dart code.
+class AngularAnalyzerPlugin implements Plugin {
+
+  /// The unique identifier for this plugin.
+  static const String UNIQUE_IDENTIFIER = 'angular2.analysis';
+
+  @override
+  String get uniqueIdentifier => UNIQUE_IDENTIFIER;
+
+  @override
+  void registerExtensionPoints(RegisterExtensionPoint registerExtensionPoint) {}
+
+  @override
+  void registerExtensions(RegisterExtension registerExtension) {
+    String taskId = TASK_EXTENSION_POINT_ID;
+    registerExtension(taskId, BuildUnitDirectivesTask.DESCRIPTOR);
+  }
+}