Fix hints reported by analyzer.

pkg/compiler/lib/src/common/resolution.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.
 
 library dart2js.common.resolution;
 
 import '../common.dart';
 import '../compile_time_constants.dart';
-import '../compiler.dart' show Compiler;
 import '../constants/expressions.dart' show ConstantExpression;
 import '../constants/values.dart' show ConstantValue;
 import '../core_types.dart' show CommonElements;
 import '../elements/resolution_types.dart' show ResolutionDartType, Types;
 import '../elements/elements.dart'
     show
         AstElement,
         ClassElement,
         Element,
         Entity,
@@ skipping 231 matching lines @@
       if (cls.isPatch) {
         patchParser.parsePatchClassNode(cls);
       }
     });
   }
 
   @override
   ScannerOptions getScannerOptionsFor(Element element) => new ScannerOptions(
       canUseNative: backend.canLibraryUseNative(element.library));
 }