Refactor the try statement analysis results.

pkg/analyzer2dart/lib/src/cps_generator.dart

 // Copyright (c) 2014, 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 analyzer2dart.cps_generator;
 
 import 'package:analyzer/analyzer.dart';
 
 import 'package:compiler/src/dart_types.dart' as dart2js;
 import 'package:compiler/src/elements/elements.dart' as dart2js;
@@ skipping 77 matching lines @@
   analyzer.LibraryElement get currentLibrary => element.library;
 
   ir.Node visit(AstNode node) => node.accept(this);
 
   ir.ConstructorDefinition handleConstructorDeclaration(
       analyzer.ConstructorElement constructor, FunctionBody body) {
     dart2js.ConstructorElement element = converter.convertElement(constructor);
     return withBuilder(
         new DartIrBuilder(DART_CONSTANT_SYSTEM,
                           element,
-                          // TODO(johnniwinther): Supported closure variables.
-                          new NullCapturedVariables()),
+                          // TODO(johnniwinther): Support closure variables.
+                          new Set<dart2js.Local>()),
         () {
       irBuilder.buildFunctionHeader(
           constructor.parameters.map(converter.convertElement));
       // Visit the body directly to avoid processing the signature as
       // expressions.
       // Call to allow for `body == null` in case of synthesized constructors.
       build(body);
       return irBuilder.makeConstructorDefinition(const [], const []);
     });
   }
 
   ir.FieldDefinition handleFieldDeclaration(
       analyzer.PropertyInducingElement field, VariableDeclaration node) {
     dart2js.FieldElement element = converter.convertElement(field);
     return withBuilder(
         new DartIrBuilder(DART_CONSTANT_SYSTEM,
                           element,
-                          // TODO(johnniwinther): Supported closure variables.
-                          new NullCapturedVariables()),
+                          // TODO(johnniwinther): Support closure variables.
+                          new Set<dart2js.Local>()),
         () {
       irBuilder.buildFieldInitializerHeader();
       ir.Primitive initializer = build(node.initializer);
       return irBuilder.makeFieldDefinition(initializer);
     });
   }
 
   ir.FunctionDefinition handleFunctionDeclaration(
       analyzer.ExecutableElement function, FunctionBody body) {
     dart2js.FunctionElement element = converter.convertElement(function);
     return withBuilder(
         new DartIrBuilder(DART_CONSTANT_SYSTEM,
                           element,
-                          // TODO(johnniwinther): Supported closure variables.
-                          new NullCapturedVariables()),
+                          // TODO(johnniwinther): Support closure variables.
+                          new Set<dart2js.Local>()),
         () {
       irBuilder.buildFunctionHeader(
           function.parameters.map(converter.convertElement));
       // Visit the body directly to avoid processing the signature as
       // expressions.
       visit(body);
       return irBuilder.makeFunctionDefinition(const []);
     });
   }
 
@@ skipping 434 matching lines @@
               catchClause.exceptionParameter.staticElement),
           buildCatchBlock: subbuild(catchClause.body)));
 
     }
     irBuilder.buildTry(
         tryStatementInfo: new TryStatementInfo(),
         buildTryBlock: subbuild(node.body),
         catchClauseInfos: catchClauseInfos);
   }
 }
-
-class NullCapturedVariables extends DartCapturedVariables {
-  NullCapturedVariables() : super(null);
-}