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

pkg/compiler/lib/src/resolution/class_members.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.resolution.compute_members;
 
+import '../common.dart';
 import '../common/names.dart' show
     Identifiers;
 import '../common/resolution.dart' show
     Resolution;
 import '../compiler.dart' show
     Compiler;
 import '../dart_types.dart';
-import '../diagnostics/diagnostic_listener.dart' show
-    DiagnosticMessage,
-    DiagnosticReporter;
-import '../diagnostics/invariant.dart' show
-    invariant;
-import '../diagnostics/messages.dart' show
-    MessageKind;
 import '../elements/elements.dart' show
     ClassElement,
     Element,
     LibraryElement,
     Member,
     MemberElement,
     MemberSignature,
     MixinApplicationElement,
     Name,
     PublicName;
@@ skipping 922 matching lines @@
         message: "Members have not been fully computed for $this."));
     if (interfaceMembersAreClassMembers) {
       classMembers.forEach((_, member) {
         if (!member.isStatic) f(member);
       });
     } else {
       interfaceMembers.forEach((_, member) => f(member));
     }
   }
 }