Various redemptions

pkg/compiler/lib/src/universe/codegen_world_builder.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;
 
 /// World builder specific to codegen.
 ///
 /// This adds additional access to liveness of selectors and elements.
 abstract class CodegenWorldBuilder implements WorldBuilder {
@@ skipping 570 matching lines @@
         .forEachInstanceField(f, includeSuperAndInjectedMembers: true);
   }
 
   @override
   void forEachParameter(MethodElement function,
       void f(DartType type, String name, ConstantValue defaultValue)) {
     FunctionSignature parameters = function.functionSignature;
     parameters.orderedForEachParameter((_parameter) {
       ParameterElement parameter = _parameter;
       ConstantValue value;
-      if (parameter.constant != null) {
+      if (parameter.isOptional) {
         value = _constants.getConstantValue(parameter.constant);
-      } else {
-        value = new NullConstantValue();
       }
       f(parameter.type, parameter.name, value);
     });
   }
 
   @override
   void _processInstantiatedClassMember(
       ClassEntity cls, MemberElement member, MemberUsedCallback memberUsed) {
     assert(member.isDeclaration, failedAt(member));
     if (member.isMalformed) return;
@@ skipping 53 matching lines @@
 
   @override
   void forEachInstanceField(
       ClassEntity cls, void f(ClassEntity declarer, FieldEntity field)) {
     _elementEnvironment.forEachClassMember(cls,
         (ClassEntity declarer, MemberEntity member) {
       if (member.isField && member.isInstanceMember) f(declarer, member);
     });
   }
 }