Update all Angular libs (run update_all.sh).

third_party/pkg/di/lib/src/error_helper.dart

Index: third_party/pkg/di/lib/src/error_helper.dart
diff --git a/third_party/pkg/di/lib/src/error_helper.dart b/third_party/pkg/di/lib/src/error_helper.dart
new file mode 100644
index 0000000000000000000000000000000000000000..c6035882ee2784c14ef08241c554596f7e989ba8
--- /dev/null
+++ b/third_party/pkg/di/lib/src/error_helper.dart
@@ -0,0 +1,23 @@
+library di.error_helper;
+
+import 'package:di/di.dart';
+import 'package:di/src/base_injector.dart';
+
+String error(ResolutionContext resolving, message, [Key appendDependency]) {
+  if (appendDependency != null) {
+    resolving = new ResolutionContext(resolving.depth + 1, appendDependency, resolving);
+  }
+
+  String graph = resolvedTypes(resolving).reversed.join(' -> ');
+
+  return '$message (resolving $graph)';
+}
+
+List<Key> resolvedTypes(ResolutionContext resolving) {
+  List resolved = [];
+  while (resolving.depth != 0) {
+    resolved.add(resolving.key);
+    resolving = resolving.parent;
+  }
+  return resolved;
+}