Serialize ResolutionImpact instead of WorldImpact.

pkg/compiler/lib/src/serialization/serialization.dart

Index: pkg/compiler/lib/src/serialization/serialization.dart
diff --git a/pkg/compiler/lib/src/serialization/serialization.dart b/pkg/compiler/lib/src/serialization/serialization.dart
index a336321494e46733287dfdb4ff64ae77aa67ae9f..6f046d4d28d0359fb5af51c423ad7390f2443493 100644
--- a/pkg/compiler/lib/src/serialization/serialization.dart
+++ b/pkg/compiler/lib/src/serialization/serialization.dart
@@ -7,6 +7,7 @@ library dart2js.serialization;
 import '../elements/elements.dart';
 import '../constants/expressions.dart';
 import '../dart_types.dart';
+import '../util/enumset.dart';
 
 import 'constant_serialization.dart';
 import 'element_serialization.dart';
@@ -103,6 +104,17 @@ abstract class AbstractEncoder<K> {
     _map[key] = new EnumValue(value);
   }
 
+  /// Maps the [key] entry to the set of enum [values] in the encoded object.
+  void setEnums(K key, Iterable values) {
+    setEnumSet(key, new EnumSet.fromValues(values));
+  }
+
+  /// Maps the [key] entry to the enum [set] in the encoded object.
+  void setEnumSet(K key, EnumSet set) {
+    _checkKey(key);
+    _map[key] = new IntValue(set.value);
+  }
+
   /// Maps the [key] entry to the [element] in the encoded object.
   void setElement(K key, Element element) {
     _checkKey(key);
@@ -321,6 +333,22 @@ abstract class AbstractDecoder<K> {
     return enumValues[value];
   }
 
+  /// Returns the set of enum values associated with [key] in the decoded
+  /// object.
+  ///
+  /// If no value is associated with [key], then if [isOptional] is `true`,
+  /// [defaultValue] is returned, otherwise an exception is thrown.
+  EnumSet getEnums(K key, {bool isOptional: false}) {
+    int value = _map[_getKeyValue(key)];
+    if (value == null) {
+      if (isOptional) {
+        return const EnumSet.fixed(0);
+      }
+      throw new StateError("enum values '$key' not found in $_map.");
+    }
+    return new EnumSet.fixed(value);
+  }
+
   /// Returns the [Element] value associated with [key] in the decoded object.
   ///
   /// If no value is associated with [key], then if [isOptional] is `true`,