Cleanup warnings in unit tests.

tests/compiler/dart2js/cpa_inference_test.dart

 // Copyright (c) 2012, 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.
 
 import 'dart:async';
 import "package:expect/expect.dart";
 import "package:async_helper/async_helper.dart";
-import 'package:compiler/implementation/source_file.dart';
 import 'package:compiler/implementation/types/types.dart';
 import 'package:compiler/implementation/inferrer/concrete_types_inferrer.dart';
 
-import "parser_helper.dart";
 import "compiler_helper.dart";
 import "type_mask_test_helper.dart";
-import 'dart:mirrors';
 
 /**
  * Finds the node corresponding to the last occurence of the substring
  * [: identifier; :] in the program represented by the visited AST.
  */
 class VariableFinderVisitor extends Visitor {
   final String identifier;
   Node result;
 
   VariableFinderVisitor(this.identifier);
@@ skipping 33 matching lines @@
     int = inferrer.baseTypes.intBaseType;
     double = inferrer.baseTypes.doubleBaseType;
     num = inferrer.baseTypes.numBaseType;
     bool = inferrer.baseTypes.boolBaseType;
     string = inferrer.baseTypes.stringBaseType;
     list = inferrer.baseTypes.listBaseType;
     growableList = inferrer.baseTypes.growableListBaseType;
     map = inferrer.baseTypes.mapBaseType;
     nullType = const NullBaseType();
     functionType = inferrer.baseTypes.functionBaseType;
-    Element mainElement = compiler.mainApp.find('main');
-    ast = mainElement.parseNode(compiler);
+    FunctionElement mainElement = compiler.mainApp.find('main');
+    ast = mainElement.node;
   }
 
   BaseType base(String className) {
     final source = className;
     return new ClassBaseType(compiler.mainApp.find(source));
   }
 
   /**
    * Finds the [Node] corresponding to the last occurence of the substring
    * [: identifier; :] in the program represented by the visited AST. For
@@ skipping 2052 matching lines @@
     testClosures10,
     testClosures11,
     testClosures12,
     testRefinement,
     testDefaultArguments,
     testSuperConstructorCall,
     testSuperConstructorCall2,
     testSuperConstructorCall3,
   ], (f) => f()));
 }