[WEB-16445] When create a missing imported library/part, add the edit once.

pkg/analysis_server/test/services/correction/fix_test.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 test.services.correction.fix;
 
 import 'package:analysis_server/edit/fix/fix_core.dart';
 import 'package:analysis_server/src/protocol.dart' hide AnalysisError;
 import 'package:analysis_server/src/services/correction/fix.dart';
 import 'package:analysis_server/src/services/correction/fix_internal.dart';
@@ skipping 1037 matching lines @@
 ''');
     AnalysisError error = _findErrorToFix();
     fix = _assertHasFix(DartFixKind.CREATE_FILE, error);
     change = fix.change;
     // validate change
     List<SourceFileEdit> fileEdits = change.edits;
     expect(fileEdits, hasLength(1));
     SourceFileEdit fileEdit = change.edits[0];
     expect(fileEdit.file, '/my/project/bin/my_file.dart');
     expect(fileEdit.fileStamp, -1);
+    expect(fileEdit.edits, hasLength(1));
     expect(fileEdit.edits[0].replacement, contains('library my.file;'));
   }
 
   void test_createFile_forPart() {
     testFile = '/my/project/bin/test.dart';
     resolveTestUnit('''
 library my.lib;
 part 'my_part.dart';
 ''');
     AnalysisError error = _findErrorToFix();
     fix = _assertHasFix(DartFixKind.CREATE_FILE, error);
     change = fix.change;
     // validate change
     List<SourceFileEdit> fileEdits = change.edits;
     expect(fileEdits, hasLength(1));
     SourceFileEdit fileEdit = change.edits[0];
     expect(fileEdit.file, '/my/project/bin/my_part.dart');
     expect(fileEdit.fileStamp, -1);
+    expect(fileEdit.edits, hasLength(1));
     expect(fileEdit.edits[0].replacement, contains('part of my.lib;'));
   }
 
   void test_createGetter_BAD_inSDK() {
     resolveTestUnit('''
 main(List p) {
   int v = p.foo;
 }
 ''');
     assertNoFix(DartFixKind.CREATE_GETTER);
@@ skipping 2557 matching lines @@
 
   List<Position> _findResultPositions(List<String> searchStrings) {
     List<Position> positions = <Position>[];
     for (String search in searchStrings) {
       int offset = resultCode.indexOf(search);
       positions.add(new Position(testFile, offset));
     }
     return positions;
   }
 }