Fix "edit.format" to follow protocol when there is no selection.

pkg/analysis_server/test/edit/format_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.edit.format;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/edit/edit_domain.dart';
 import 'package:analysis_server/src/plugin/server_plugin.dart';
@@ skipping 28 matching lines @@
   int x = 3;
 }
 ''');
     return waitForTasksFinished().then((_) {
       EditFormatResult formatResult = _formatAt(0, 3);
       expect(formatResult.edits, isNotNull);
       expect(formatResult.edits, hasLength(0));
     });
   }
 
+  Future test_formatNoSelection() async {
+    addTestFile('''
+main() { int x = 3; }
+''');
+    await waitForTasksFinished();
+    EditFormatResult formatResult = _formatAt(0, 0);
+
+    expect(formatResult.edits, isNotNull);
+    expect(formatResult.edits, hasLength(1));
+
+    SourceEdit edit = formatResult.edits[0];
+    expect(edit.replacement, equals('''
+main() {
+  int x = 3;
+}
+'''));
+    expect(formatResult.selectionOffset, equals(0));
+    expect(formatResult.selectionLength, equals(0));
+  }
+
   Future test_formatSimple() {
     addTestFile('''
 main() { int x = 3; }
 ''');
     return waitForTasksFinished().then((_) {
       EditFormatResult formatResult = _formatAt(0, 3);
 
       expect(formatResult.edits, isNotNull);
       expect(formatResult.edits, hasLength(1));
 
       SourceEdit edit = formatResult.edits[0];
       expect(edit.replacement, equals('''
 main() {
   int x = 3;
 }
 '''));
       expect(formatResult.selectionOffset, equals(0));
       expect(formatResult.selectionLength, equals(3));
     });
   }
 
   EditFormatResult _formatAt(int selectionOffset, int selectionLength) {
     Request request = new EditFormatParams(
         testFile, selectionOffset, selectionLength).toRequest('0');
     Response response = handleSuccessfulRequest(request);
     return new EditFormatResult.fromResponse(response);
   }
 }