No more warnings for duplicate unnamed lib imports.

pkg/analyzer/lib/src/generated/error_verifier.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 engine.resolver.error_verifier;
 
 import 'dart:collection';
 import "dart:math" as math;
 
 import 'package:analyzer/src/generated/static_type_analyzer.dart';
@@ skipping 2981 matching lines @@
   bool _checkForExportDuplicateLibraryName(ExportDirective directive,
       ExportElement exportElement, LibraryElement exportedLibrary) {
     if (exportedLibrary == null) {
       return false;
     }
     String name = exportedLibrary.name;
     // check if there is other exported library with the same name
     LibraryElement prevLibrary = _nameToExportElement[name];
     if (prevLibrary != null) {
       if (prevLibrary != exportedLibrary) {
-        if (name.isEmpty) {
-          _errorReporter.reportErrorForNode(
-              StaticWarningCode.EXPORT_DUPLICATED_LIBRARY_UNNAMED, directive, [
-            prevLibrary.definingCompilationUnit.displayName,
-            exportedLibrary.definingCompilationUnit.displayName
-          ]);
-        } else {
+        if (!name.isEmpty) {
           _errorReporter.reportErrorForNode(
               StaticWarningCode.EXPORT_DUPLICATED_LIBRARY_NAMED, directive, [
             prevLibrary.definingCompilationUnit.displayName,
             exportedLibrary.definingCompilationUnit.displayName,
             name
           ]);
         }
         return true;
       }
     } else {
@@ skipping 486 matching lines @@
     // prepare imported library
     LibraryElement nodeLibrary = importElement.importedLibrary;
     if (nodeLibrary == null) {
       return false;
     }
     String name = nodeLibrary.name;
     // check if there is another imported library with the same name
     LibraryElement prevLibrary = _nameToImportElement[name];
     if (prevLibrary != null) {
       if (prevLibrary != nodeLibrary) {
-        if (name.isEmpty) {
-          _errorReporter.reportErrorForNode(
-              StaticWarningCode.IMPORT_DUPLICATED_LIBRARY_UNNAMED, directive, [
-            prevLibrary.definingCompilationUnit.displayName,
-            nodeLibrary.definingCompilationUnit.displayName
-          ]);
-        } else {
+        if (!name.isEmpty) {
           _errorReporter.reportErrorForNode(
               StaticWarningCode.IMPORT_DUPLICATED_LIBRARY_NAMED, directive, [
             prevLibrary.definingCompilationUnit.displayName,
             nodeLibrary.definingCompilationUnit.displayName,
             name
           ]);
         }
         return true;
       }
     } else {
@@ skipping 2460 matching lines @@
     toCheck.add(type.element);
     // type arguments
     if (type is InterfaceType) {
       InterfaceType interfaceType = type;
       for (DartType typeArgument in interfaceType.typeArguments) {
         _addTypeToCheck(typeArgument);
       }
     }
   }
 }