Clarify presentation of the target in retaining paths.

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

Index: runtime/observatory/lib/src/elements/objectpool_view.dart
diff --git a/runtime/observatory/lib/src/elements/objectpool_view.dart b/runtime/observatory/lib/src/elements/objectpool_view.dart
index 43f649b0b88ac1f728a74e9f4fdd4032ae01650a..86204397938a9b1e867eea8880d9f77402963b06 100644
--- a/runtime/observatory/lib/src/elements/objectpool_view.dart
+++ b/runtime/observatory/lib/src/elements/objectpool_view.dart
@@ -172,6 +172,6 @@ class ObjectPoolViewElement extends HtmlElement implements Renderable {
             ..text = 'NativeEntry 0x${entry.asInteger.toRadixString(16)}'
         ];
     }
-    throw new Exception('Unkown ObjectPoolEntryKind (${entry.kind})');
+    throw new Exception('Unknown ObjectPoolEntryKind (${entry.kind})');
   }
 }