Adding Angular and dependent packages for testing

third_party/pkg/angular/lib/tools/source_crawler.dart

Index: third_party/pkg/angular/lib/tools/source_crawler.dart
diff --git a/third_party/pkg/angular/lib/tools/source_crawler.dart b/third_party/pkg/angular/lib/tools/source_crawler.dart
new file mode 100644
index 0000000000000000000000000000000000000000..ffbe437979321ecb98d32945b0b1fe8c5319877f
--- /dev/null
+++ b/third_party/pkg/angular/lib/tools/source_crawler.dart
@@ -0,0 +1,13 @@
+library source_crawler;
+
+import 'package:analyzer/src/generated/ast.dart';
+
+typedef CompilationUnitVisitor(CompilationUnit cu);
+
+/**
+ * Dart source file crawler. As it crawls Dart source, it calls
+ * [CompilationUnitVisitor] on each file.
+ */
+abstract class SourceCrawler {
+  void crawl(String entryPoint, CompilationUnitVisitor visitor);
+}