Fix for explicit dart:core import.

pkg/analyzer/test/src/task/dart_test.dart

 // Copyright (c) 2015, 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 test.src.task.dart_test;
 
 import 'package:analyzer/src/context/cache.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/constant.dart';
 import 'package:analyzer/src/generated/element.dart';
@@ skipping 342 matching lines @@
       expect(exportElement.uriOffset, 41);
       expect(exportElement.uriEnd, 52);
     }
     // validate LibraryElement
     expect(libraryElementA.hasExtUri, isFalse);
     // has an artificial "dart:core" import
     {
       List<ImportElement> imports = libraryElementA.imports;
       expect(imports, hasLength(2));
       expect(imports[1].importedLibrary.isDartCore, isTrue);
+      expect(imports[1].isSynthetic, isTrue);
     }
   }
 
   test_perform_combinators() {
     List<Source> sources = newSources({
       '/libA.dart': '''
 library libA;
 import 'libB.dart' show A, B hide C, D;
 ''',
       '/libB.dart': '''
@@ skipping 72 matching lines @@
 '''
     });
     Source sourceA = sources[0];
     // perform task
     computeResult(sourceA, LIBRARY_ELEMENT2);
     expect(task, new isInstanceOf<BuildDirectiveElementsTask>());
     // validate errors
     _assertErrorsWithCodes([CompileTimeErrorCode.IMPORT_OF_NON_LIBRARY]);
   }
 
+  test_perform_explicitDartCoreImport() {
+    List<Source> sources = newSources({
+      '/lib.dart': '''
+library lib;
+import 'dart:core' show List;
+'''
+    });
+    Source source = sources[0];
+    // perform task
+    computeResult(source, LIBRARY_ELEMENT2);
+    expect(task, new isInstanceOf<BuildDirectiveElementsTask>());
+    // prepare outputs
+    LibraryElement libraryElement = outputs[LIBRARY_ELEMENT2];
+    // has an explicit "dart:core" import
+    {
+      List<ImportElement> imports = libraryElement.imports;
+      expect(imports, hasLength(1));
+      expect(imports[0].importedLibrary.isDartCore, isTrue);
+      expect(imports[0].isSynthetic, isFalse);
+    }
+  }
+
   test_perform_hasExtUri() {
     List<Source> sources = newSources({
       '/lib.dart': '''
 import 'dart-ext:doesNotExist.dart';
 '''
     });
     Source source = sources[0];
     // perform task
     computeResult(source, LIBRARY_ELEMENT2);
     expect(task, new isInstanceOf<BuildDirectiveElementsTask>());
@@ skipping 2264 matching lines @@
   /**
    * Fill [errorListener] with [result] errors in the current [task].
    */
   void _fillErrorListener(ResultDescriptor<List<AnalysisError>> result) {
     List<AnalysisError> errors = task.outputs[result];
     expect(errors, isNotNull, reason: result.name);
     errorListener = new GatheringErrorListener();
     errorListener.addAll(errors);
   }
 }