fix(transformer): Support prefixed annotations in the transformer.

closes https://github.com/angular/angular/issues/2754

modules/angular2/test/transform/common/annotation_matcher_test.dart

@@ -0,0 +1,104 @@
+library angular2.test.transform.common.annotation_matcher_test;
+
+import 'dart:async';
+import 'package:analyzer/analyzer.dart';
+import 'package:angular2/src/transform/common/annotation_matcher.dart';
+import 'package:barback/barback.dart' show AssetId;
+import 'package:guinness/guinness.dart';
+
+main() {
+  allTests();
+}
+
+var simpleAst = parseCompilationUnit('''
+import 'package:test/test.dart';
+
+@Test()
+var foo;
+''');
+
+var namespacedAst = parseCompilationUnit('''
+import 'package:test/test.dart' as test;
+
+@test.Test()
+var foo;
+''');
+
+var relativePathAst = parseCompilationUnit('''
+import 'test.dart';
+
+@Test()
+var foo;
+''');
+
+var namespacedRelativePathAst = parseCompilationUnit('''
+import 'test.dart' as test;
+
+@test.Test()
+var foo;
+''');
+
+void allTests() {
+  it('should be able to match basic annotations.', () {
+    var matcher = new AnnotationMatcher()
+      ..add(const AnnotationDescriptor('Test', 'package:test/test.dart', null));
+    var visitor = new MatchRecordingVisitor(matcher);
+    simpleAst.accept(visitor);
+    expect(visitor.matches.length).toBe(1);
+  });
+
+  it('should be able to match namespaced annotations.', () {
+    var matcher = new AnnotationMatcher()
+      ..add(const AnnotationDescriptor('Test', 'package:test/test.dart', null));
+    var visitor = new MatchRecordingVisitor(matcher);
+    namespacedAst.accept(visitor);
+    expect(visitor.matches.length).toBe(1);
+  });
+
+  it('should be able to match relative imports.', () {
+    var matcher = new AnnotationMatcher()
+      ..add(const AnnotationDescriptor('Test', 'package:test/test.dart', null));
+    var visitor =
+        new MatchRecordingVisitor(matcher, new AssetId('test', 'lib/foo.dart'));
+    relativePathAst.accept(visitor);
+    expect(visitor.matches.length).toBe(1);
+  });
+
+  it('should be able to match relative imports with a namespace.', () {
+    var matcher = new AnnotationMatcher()
+      ..add(const AnnotationDescriptor('Test', 'package:test/test.dart', null));
+    var visitor =
+        new MatchRecordingVisitor(matcher, new AssetId('test', 'lib/foo.dart'));
+    namespacedRelativePathAst.accept(visitor);
+    expect(visitor.matches.length).toBe(1);
+  });
+
+  it('should not match annotations if the import is missing.', () {
+    var matcher = new AnnotationMatcher()
+      ..add(const AnnotationDescriptor('Test', 'package:test/foo.dart', null));
+    var visitor = new MatchRecordingVisitor(matcher);
+    simpleAst.accept(visitor);
+    expect(visitor.matches.isEmpty).toBeTrue();
+  });
+
+  it('should not match annotations if the name is different.', () {
+    var matcher = new AnnotationMatcher()
+      ..add(const AnnotationDescriptor('Foo', 'package:test/test.dart', null));
+    var visitor = new MatchRecordingVisitor(matcher);
+    simpleAst.accept(visitor);
+    expect(visitor.matches.isEmpty).toBeTrue();
+  });
+}
+
+class MatchRecordingVisitor extends RecursiveAstVisitor {
+  final AssetId assetId;
+  final AnnotationMatcher matcher;
+  final List<Annotation> matches = [];
+
+  MatchRecordingVisitor(this.matcher, [this.assetId]) : super();
+
+  @override
+  void visitAnnotation(Annotation annotation) {
+    if (matcher.hasMatch(annotation, assetId)) matches.add(annotation);
+  }
+}