Deserialize ResolvedAsts and ResolutionImpacts only when needed for compilation.

tests/compiler/dart2js/serialization/reserialization_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.reserialization_test;
 
 import 'dart:async';
 import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/compiler.dart';
 import 'package:compiler/src/diagnostics/invariant.dart';
@@ skipping 20 matching lines @@
 }
 
 Future testReserialization(Uri entryPoint) async {
   SerializationResult result1 = await serialize(entryPoint);
   Compiler compiler1 = result1.compiler;
   SerializedData serializedData1 = result1.serializedData;
   Iterable<LibraryElement> libraries1 = compiler1.libraryLoader.libraries;
 
   SerializationResult result2 = await serialize(entryPoint,
       memorySourceFiles: serializedData1.toMemorySourceFiles(),
-      resolutionInputs: serializedData1.toUris());
+      resolutionInputs: serializedData1.toUris(),
+      deserializeCompilationDataForTesting: true);
   Compiler compiler2 = result2.compiler;
   SerializedData serializedData2 = result2.serializedData;
   Iterable<LibraryElement> libraries2 = compiler2.libraryLoader.libraries;
 
   SerializationResult result3 = await serialize(entryPoint,
       memorySourceFiles: serializedData2.toMemorySourceFiles(),
-      resolutionInputs: serializedData2.toUris());
+      resolutionInputs: serializedData2.toUris(),
+      deserializeCompilationDataForTesting: true);
   Compiler compiler3 = result3.compiler;
   Iterable<LibraryElement> libraries3 = compiler3.libraryLoader.libraries;
 
   for (LibraryElement library1 in libraries1) {
     LibraryElement library2 = libraries2.firstWhere((LibraryElement library2) {
       return library2.canonicalUri == library1.canonicalUri;
     });
     Expect.isNotNull(library2,
         "No library found for ${library1.canonicalUri}.");
     checkLibraryContent('library1', 'library2', 'library', library1, library2);
 
     LibraryElement library3 = libraries3.firstWhere((LibraryElement library3) {
       return library3.canonicalUri == library1.canonicalUri;
     });
     Expect.isNotNull(library3,
         "No library found for ${library1.canonicalUri}.");
     checkLibraryContent('library1', 'library3', 'library', library1, library3);
   }
 
   checkAllResolvedAsts(compiler1, compiler2);
   checkAllResolvedAsts(compiler1, compiler3);
 
   checkAllImpacts(compiler1, compiler2);
   checkAllImpacts(compiler1, compiler3);
 }