Support deserialized compilation of the empty program.

pkg/compiler/lib/src/common/resolution.dart

 // Copyright (c) 2012, 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.common.resolution;
 
 import '../common.dart';
 import '../compiler.dart' show Compiler;
 import '../constants/expressions.dart' show ConstantExpression;
 import '../core_types.dart' show CoreTypes;
@@ skipping 164 matching lines @@
     return type == other.type &&
         isConstant == other.isConstant &&
         isEmpty == other.isEmpty;
   }
 
   String toString() {
     return 'ListLiteralUse($type,isConstant:$isConstant,isEmpty:$isEmpty)';
   }
 }
 
+/// Interface for the accessing the front-end analysis.
+// TODO(johnniwinther): Find a better name for this.
+abstract class Frontend {
+  /// Returns the `ResolvedAst` for the [element].
+  ResolvedAst getResolvedAst(Element element);
+
+  /// Returns the [ResolutionImpact] for [element].
+  ResolutionImpact getResolutionImpact(Element element);
+}
+
 // TODO(johnniwinther): Rename to `Resolver` or `ResolverContext`.
-abstract class Resolution {
+abstract class Resolution implements Frontend {
   Parsing get parsing;
   DiagnosticReporter get reporter;
   CoreTypes get coreTypes;
 
   /// If set to `true` resolution caches will not be cleared. Use this only for
   /// testing.
   bool retainCachesForTesting;
 
   void resolveTypedef(TypedefElement typdef);
   void resolveClass(ClassElement cls);
@@ skipping 36 matching lines @@
 }
 
 // TODO(johnniwinther): Rename to `Parser` or `ParsingContext`.
 abstract class Parsing {
   DiagnosticReporter get reporter;
   void parsePatchClass(ClassElement cls);
   measure(f());
   ScannerOptions getScannerOptionsFor(Element element);
   ParserOptions get parserOptions;
 }