Ignore not existing parts.

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 881 matching lines @@
       '/partB.dart': '''
 part of libB;
 '''
     });
     _assertErrorsWithCodes(
         [ResolverErrorCode.MISSING_LIBRARY_DIRECTIVE_WITH_PART]);
     AnalysisError error = errorListener.errors[0];
     expect(error.getProperty(ErrorProperty.PARTS_LIBRARY_NAME), isNull);
   }
 
+  test_perform_error_partDoesNotExist() {
+    _performBuildTask({
+      '/lib.dart': '''
+library lib;
+part 'part.dart';
+'''
+    });
+    // we already report URI_DOES_NOT_EXIST, no need to report other errors
+    _assertErrorsWithCodes([]);
+  }
+
   test_perform_error_partOfDifferentLibrary() {
     _performBuildTask({
       '/lib.dart': '''
 library lib;
 part 'part.dart';
 ''',
       '/part.dart': '''
 part of someOtherLib;
 '''
     });
@@ skipping 1612 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);
   }
 }