Remove Compiler.mainApp and Compiler.mainFunction

tests/compiler/dart2js/serialization/native_data_test.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dart2js.serialization.native_data_test;
 
 import 'dart:async';
 import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/common/names.dart';
 import 'package:compiler/src/commandline_options.dart';
@@ skipping 18 matching lines @@
   });
 }
 
 Future checkNativeData(Uri uri, {bool verbose: false}) async {
   print('------------------------------------------------------------------');
   print('analyze normal: $uri');
   print('------------------------------------------------------------------');
   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');
   print('------------------------------------------------------------------');
   Compiler compiler2 = compilerFor(
       memorySourceFiles: serializedData.toMemorySourceFiles(),
       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;
   NativeBasicDataImpl nativeBasicData1 = backend1.nativeBasicData;
   NativeBasicDataImpl nativeBasicData2 = backend2.nativeBasicData;
   NativeDataImpl nativeData1 = closedWorld1.nativeData;
   NativeDataImpl nativeData2 = closedWorld2.nativeData;
 
   checkMaps(
       nativeData1.jsInteropLibraryNames,
@@ skipping 40 matching lines @@
       verbose: verbose);
 
   checkMaps(
       nativeData1.nativeFieldStoreBehavior,
       nativeData2.nativeFieldStoreBehavior,
       "NativeData.nativeFieldStoreBehavior",
       areElementsEquivalent,
       testNativeBehavior,
       verbose: verbose);
 }