Refactor the try statement analysis results.

pkg/analyzer2dart/lib/src/cps_generator.dart

Index: pkg/analyzer2dart/lib/src/cps_generator.dart
diff --git a/pkg/analyzer2dart/lib/src/cps_generator.dart b/pkg/analyzer2dart/lib/src/cps_generator.dart
index 4ad4fc642f8cdc87446d1c8639ad98c5e27f8c8d..2360c161bbe1874f733d5df5462d5beb7b5c06f5 100644
--- a/pkg/analyzer2dart/lib/src/cps_generator.dart
+++ b/pkg/analyzer2dart/lib/src/cps_generator.dart
@@ -95,8 +95,8 @@ class CpsGeneratingVisitor extends SemanticVisitor<ir.Node>
     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));
@@ -114,8 +114,8 @@ class CpsGeneratingVisitor extends SemanticVisitor<ir.Node>
     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);
@@ -129,8 +129,8 @@ class CpsGeneratingVisitor extends SemanticVisitor<ir.Node>
     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));
@@ -585,7 +585,3 @@ class CpsGeneratingVisitor extends SemanticVisitor<ir.Node>
         catchClauseInfos: catchClauseInfos);
   }
 }
-
-class NullCapturedVariables extends DartCapturedVariables {
-  NullCapturedVariables() : super(null);
-}