ignore `@proxy` in strong mode

pkg/analyzer/test/src/task/strong/strong_test_helper.dart

Index: pkg/analyzer/test/src/task/strong/strong_test_helper.dart
diff --git a/pkg/analyzer/test/src/task/strong/strong_test_helper.dart b/pkg/analyzer/test/src/task/strong/strong_test_helper.dart
index 0dae12ebebcda781c22eb076d3d5c9a634046fdd..43b66d9a51fe105a6b3e9ad812a9aabc7bc10068 100644
--- a/pkg/analyzer/test/src/task/strong/strong_test_helper.dart
+++ b/pkg/analyzer/test/src/task/strong/strong_test_helper.dart
@@ -345,8 +345,6 @@ class AbstractStrongTest {
         var analysisResult = await _resolve(source);
 
         errors.addAll(analysisResult.errors.where((e) =>
-            // TODO(jmesserly): these are usually intentional dynamic calls.
-            e.errorCode.name != 'UNDEFINED_METHOD' &&
             // We don't care about any of these:
             e.errorCode != HintCode.UNUSED_ELEMENT &&
             e.errorCode != HintCode.UNUSED_FIELD &&