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

pkg/compiler/lib/src/resolution/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.members;
 
+import '../common.dart';
 import '../common/names.dart' show
     Selectors;
 import '../compiler.dart' show
     Compiler;
 import '../constants/constructors.dart' show
     RedirectingFactoryConstantConstructor;
 import '../constants/expressions.dart';
 import '../constants/values.dart';
 import '../core_types.dart';
 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 '../diagnostics/spannable.dart' show
-    Spannable;
 import '../elements/elements.dart';
 import '../elements/modelx.dart' show
     ConstructorElementX,
     ErroneousElementX,
     FunctionElementX,
     JumpTargetX,
     LocalFunctionElementX,
     LocalParameterElementX,
     LocalVariableElementX,
     MethodElementX,
@@ skipping 4655 matching lines @@
     }
     return const NoneResult();
   }
 }
 
 /// Looks up [name] in [scope] and unwraps the result.
 Element lookupInScope(DiagnosticReporter reporter, Node node,
                       Scope scope, String name) {
   return Elements.unwrap(scope.lookup(name), reporter, node);
 }