Add ElementCodegenWorldBuilder

pkg/compiler/lib/src/elements/entities.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 entities;
 
 import '../common.dart';
+import '../universe/call_structure.dart' show CallStructure;
 
 /// Abstract interface for entities.
 ///
 /// Implement this directly if the entity is not a Dart language entity.
 /// Entities defined within the Dart language should implement [Element].
 ///
 /// For instance, the JavaScript backend need to create synthetic variables for
 /// calling intercepted classes and such variables do not correspond to an
 /// entity in the Dart source code nor in the terminology of the Dart language
 /// and should therefore implement [Entity] directly.
@@ skipping 158 matching lines @@
   const ParameterStructure(
       this.requiredParameters, this.positionalParameters, this.namedParameters);
 
   const ParameterStructure.getter() : this(0, 0, const <String>[]);
 
   const ParameterStructure.setter() : this(1, 1, const <String>[]);
 
   /// The number of optional parameters (positional or named).
   int get optionalParameters =>
       positionalParameters - requiredParameters + namedParameters.length;
+
+  /// Returns the [CallStructure] corresponding to a call site passing all
+  /// parameters both required and optional.
+  CallStructure get callStructure {
+    return new CallStructure(
+        positionalParameters + namedParameters.length, namedParameters);
+  }
 }