Handle local files better in server mode

test/codegen/expect/collection/wrappers.txt

Index: test/codegen/expect/collection/wrappers.txt
diff --git a/test/codegen/expect/collection/wrappers.txt b/test/codegen/expect/collection/wrappers.txt
index 4baa7d19c7c2239a178b36e769c10f6a3d48beb8..660a90d7948631692692f02bf9735c60381911fd 100644
--- a/test/codegen/expect/collection/wrappers.txt
+++ b/test/codegen/expect/collection/wrappers.txt
@@ -4,7 +4,7 @@ severe: [INVALID_METHOD_OVERRIDE] Invalid override. The type of _DelegatingItera
 severe: [AnalyzerMessage] Missing concrete implementation of 'Iterable.expand' and 'Iterable.map' (package:collection/wrappers.dart, line 117, col 7)
 severe: [INVALID_METHOD_OVERRIDE] Base class introduces an invalid override. The type of _DelegatingIterableBase.expand (((E) → Iterable<dynamic>) → Iterable<dynamic>) is not a subtype of Iterable<E>.expand (<T>((E) → Iterable<T>) → Iterable<T>). (package:collection/wrappers.dart, line 117, col 25)
 severe: [INVALID_METHOD_OVERRIDE] Base class introduces an invalid override. The type of _DelegatingIterableBase.map (((E) → dynamic) → Iterable<dynamic>) is not a subtype of Iterable<E>.map (<T>((E) → T) → Iterable<T>). (package:collection/wrappers.dart, line 117, col 25)
-severe: [AnalyzerMessage] Missing concrete implementation of 'Iterable.map' and 'Iterable.expand' (package:collection/wrappers.dart, line 216, col 7)
+severe: [AnalyzerMessage] Missing concrete implementation of 'Iterable.expand' and 'Iterable.map' (package:collection/wrappers.dart, line 216, col 7)
 severe: [INVALID_METHOD_OVERRIDE] Base class introduces an invalid override. The type of _DelegatingIterableBase.expand (((E) → Iterable<dynamic>) → Iterable<dynamic>) is not a subtype of Iterable<E>.expand (<T>((E) → Iterable<T>) → Iterable<T>). (package:collection/wrappers.dart, line 216, col 24)
 severe: [INVALID_METHOD_OVERRIDE] Base class introduces an invalid override. The type of _DelegatingIterableBase.map (((E) → dynamic) → Iterable<dynamic>) is not a subtype of Iterable<E>.map (<T>((E) → T) → Iterable<T>). (package:collection/wrappers.dart, line 216, col 24)
 severe: [AnalyzerMessage] Missing concrete implementation of 'Iterable.map' and 'Iterable.expand' (package:collection/wrappers.dart, line 269, col 7)