Remove Compiler.mainApp and Compiler.mainFunction

tests/compiler/dart2js/serialization/native_data_test.dart

Index: tests/compiler/dart2js/serialization/native_data_test.dart
diff --git a/tests/compiler/dart2js/serialization/native_data_test.dart b/tests/compiler/dart2js/serialization/native_data_test.dart
index e6d89ad48b31fff27972704a693aaf576fd8194b..9343e178e3baa9cf5e2ebe47e67eb6e6a69bca7f 100644
--- a/tests/compiler/dart2js/serialization/native_data_test.dart
+++ b/tests/compiler/dart2js/serialization/native_data_test.dart
@@ -36,7 +36,9 @@ Future checkNativeData(Uri uri, {bool verbose: false}) async {
   SerializationResult result = await serialize(uri);
   Compiler compiler1 = result.compiler;
   SerializedData serializedData = result.serializedData;
-  ClosedWorld closedWorld1 = compiler1.closeResolution().closedWorld;
+  var elementEnvironment1 = compiler1.frontendStrategy.elementEnvironment;
+  ClosedWorld closedWorld1 =
+      compiler1.closeResolution(elementEnvironment1.mainFunction).closedWorld;
 
   print('------------------------------------------------------------------');
   print('analyze deserialized: $uri');
@@ -46,7 +48,9 @@ Future checkNativeData(Uri uri, {bool verbose: false}) async {
       resolutionInputs: serializedData.toUris(),
       options: [Flags.analyzeAll]);
   await compiler2.run(uri);
-  ClosedWorld closedWorld2 = compiler2.closeResolution().closedWorld;
+  var elementEnvironment2 = compiler2.frontendStrategy.elementEnvironment;
+  ClosedWorld closedWorld2 =
+      compiler2.closeResolution(elementEnvironment2.mainFunction).closedWorld;
 
   JavaScriptBackend backend1 = compiler1.backend;
   JavaScriptBackend backend2 = compiler2.backend;