Add ConstantUse to WorldImpact

pkg/compiler/lib/src/universe/member_usage.dart

 // Copyright (c) 2017, 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.
 
 part of world_builder;
 
 abstract class _AbstractUsage<T> {
   final EnumSet<T> _pendingUse = new EnumSet<T>();
 
   _AbstractUsage() {
@@ skipping 240 matching lines @@
 
   @override
   bool get fullyUsed => hasWrite;
 
   @override
   EnumSet<MemberUse> write() {
     if (hasWrite) {
       return MemberUses.NONE;
     }
     hasWrite = true;
-    return MemberUses.NORMAL_ONLY;
+    return _pendingUse.removeAll(MemberUses.NORMAL_ONLY);

[Johnni Winther, 2017/03/13 11:24:10]

A fix from another CL.

   }
 
   @override
   EnumSet<MemberUse> fullyUse() => write();
 }
 
 /// Enum class for the possible kind of use of [MemberEntity] objects.
 enum MemberUse { NORMAL, CLOSURIZE_INSTANCE, CLOSURIZE_STATIC }
 
 /// Common [EnumSet]s used for [MemberUse].
@@ skipping 100 matching lines @@
     if (hasClosurization) {
       return MemberUses.NONE;
     }
     hasNormalUse = hasClosurization = true;
     return _pendingUse.removeAll(MemberUses.ALL_STATIC);
   }
 
   @override
   EnumSet<MemberUse> get _originalUse => MemberUses.ALL_STATIC;
 }