Clarify presentation of the target in retaining paths.

runtime/observatory/lib/src/elements/error_view.dart

Index: runtime/observatory/lib/src/elements/error_view.dart
diff --git a/runtime/observatory/lib/src/elements/error_view.dart b/runtime/observatory/lib/src/elements/error_view.dart
index 7d9363709ca7c4437c796e9e0d446bd582090a22..cfc4cd95975677146cfafda96dec6d7c47ca168c 100644
--- a/runtime/observatory/lib/src/elements/error_view.dart
+++ b/runtime/observatory/lib/src/elements/error_view.dart
@@ -89,6 +89,6 @@ class ErrorViewElement extends HtmlElement implements Renderable {
       case M.ErrorKind.terminationError:
         return 'Termination Error';
     }
-    throw new Exception('Unkown M.ErrorKind ($kind)');
+    throw new Exception('Unknown M.ErrorKind ($kind)');
   }
 }