Use common.dart to re-export commonly used entities.

pkg/compiler/lib/src/deferred_load.dart

 // Copyright (c) 2014, 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 deferred_load;
 
+import 'common.dart';
 import 'common/backend_api.dart' show
     Backend;
-import 'common/resolution.dart' show
-    Resolution;
 import 'common/tasks.dart' show
     CompilerTask;
 import 'compiler.dart' show
     Compiler;
 import 'constants/values.dart' show
     ConstantValue,
     ConstructedConstantValue,
     DeferredConstantValue,
     StringConstantValue;
 import 'dart_types.dart';
-import 'diagnostics/messages.dart' show
-    MessageKind;
-import 'diagnostics/spannable.dart' show
-    Spannable;
 import 'elements/elements.dart' show
     AccessorElement,
     AstElement,
     ClassElement,
     Element,
     ElementKind,
     Elements,
     ExportElement,
     FunctionElement,
     ImportElement,
@@ skipping 905 matching lines @@
     return result;
   }
 
   bool operator ==(other) {
     if (other is! _DeclaredDeferredImport) return false;
     return declaration == other.declaration;
   }
 
   int get hashCode => declaration.hashCode * 17;
 }