Remove the checker and corresponding dead code

lib/src/codegen/reify_coercions.dart

 // Copyright (c) 2015, 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 dev_compiler.src.codegen.reify_coercions;
 
 import 'package:analyzer/analyzer.dart' as analyzer;
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
+import 'package:analyzer/src/task/strong/rules.dart';
 import 'package:logging/logging.dart' as logger;
 
-import '../checker/rules.dart';
 import '../info.dart';
 
 import 'ast_builder.dart';
 
 final _log = new logger.Logger('dev_compiler.reify_coercions');
 
 // TODO(leafp) Factor this out or use an existing library
 class Tuple2<T0, T1> {
   final T0 e0;
   final T1 e1;
@@ skipping 470 matching lines @@
     var t = _mkNewTypeName(dType, id, args);
     return t;
   }
 
   TypeName _mkNewTypeName(DartType type, Identifier id, List<TypeName> args) {
     var t = AstBuilder.typeName(id, args);
     t.type = type;
     return t;
   }
 }