[infra] Fix approve_results crashing on approvals for deleted tests.

Change-Id: If269731bc7ac76d6ffd624eb02f51aed1f446d27
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/97624
Reviewed-by: William Hesse <whesse@google.com>
diff --git a/tools/approve_results.dart b/tools/approve_results.dart
index 67554a7..1b105af 100755
--- a/tools/approve_results.dart
+++ b/tools/approve_results.dart
@@ -96,7 +96,7 @@
   String get baselineResult => (baselineData ?? const {})["result"];
   String get approvedResult => (approvedResultData ?? const {})["result"];
   bool get isDifferent => result != null && result != baselineResult;
-  bool get isApproved => result == approvedResult;
+  bool get isApproved => result == null || result == approvedResult;
   List<String> get flakyModes =>
       flakinessData != null ? flakinessData["outcomes"].cast<String>() : null;
   bool get isFlake => flakinessData != null && flakyModes.contains(result);