Add DartWorkManager to manage Dart-specific results computation scheduling.

pkg/analyzer/test/generated/test_support.dart

Index: pkg/analyzer/test/generated/test_support.dart
diff --git a/pkg/analyzer/test/generated/test_support.dart b/pkg/analyzer/test/generated/test_support.dart
index e5a05d06a128c068b412c7366959ec1167c607fa..12354d3988d36c33f68c1de635575ccfbf5d7d93 100644
--- a/pkg/analyzer/test/generated/test_support.dart
+++ b/pkg/analyzer/test/generated/test_support.dart
@@ -594,6 +594,8 @@ class TestSource extends Source {
   UriKind get uriKind {
     throw new UnsupportedOperationException();
   }
+  @override
+  String toString() => '$_name';
   bool operator ==(Object other) {
     if (other is TestSource) {
       return other._name == _name;