Remove the checker and corresponding dead code

lib/src/codegen/code_generator.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.code_generator;
 
 import 'package:analyzer/src/generated/element.dart'
     show CompilationUnitElement, LibraryElement;
 import 'package:analyzer/src/generated/engine.dart' show AnalysisContext;
+import 'package:analyzer/src/task/strong/rules.dart';
 import 'package:path/path.dart' as path;
 
 import '../compiler.dart' show AbstractCompiler;
 import '../info.dart';
 import '../utils.dart' show canonicalLibraryName;
-import '../checker/rules.dart';
 import '../options.dart' show CodegenOptions;
 
 abstract class CodeGenerator {
   final AbstractCompiler compiler;
   final TypeRules rules;
   final AnalysisContext context;
   final CodegenOptions options;
 
   CodeGenerator(AbstractCompiler compiler)
       : compiler = compiler,
@@ skipping 94 matching lines @@
       // Not a package.
       // TODO(leafp) These may need to be adjusted
       // relative to the import location
       return new Uri(path: suffix);
     }
     assert(index == 0);
     return new Uri(
         scheme: 'package', path: path.joinAll(parts.sublist(index + 1)));
   }
 }