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

pkg/analysis_server/lib/src/edit/edit_domain.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 edit.domain;
 
 import 'dart:async';
 
 import 'package:analysis_server/edit/assist/assist_core.dart';
 import 'package:analysis_server/edit/fix/fix_core.dart';
@@ skipping 92 matching lines @@
 
     List<SourceEdit> edits = <SourceEdit>[];
 
     if (formattedSource != unformattedSource) {
       //TODO: replace full replacements with smaller, more targeted edits
       SourceEdit edit =
           new SourceEdit(0, unformattedSource.length, formattedSource);
       edits.add(edit);
     }
 
-    return new EditFormatResult(edits, formattedResult.selectionStart,
-        formattedResult.selectionLength).toResponse(request.id);
+    int newStart = formattedResult.selectionStart;
+    int newLength = formattedResult.selectionLength;
+
+    // Sending null start/length values would violate protocol, so convert back
+    // to 0.
+    if (newStart == null) {
+      newStart = 0;
+    }
+    if (newLength == null) {
+      newLength = 0;
+    }
+
+    return new EditFormatResult(edits, newStart,
+        newLength).toResponse(request.id);
   }
 
   Response getAssists(Request request) {
     EditGetAssistsParams params = new EditGetAssistsParams.fromRequest(request);
     ContextSourcePair pair = server.getContextSourcePair(params.file);
     engine.AnalysisContext context = pair.context;
     Source source = pair.source;
     List<SourceChange> changes = <SourceChange>[];
     if (context != null && source != null) {
       List<Assist> assists = computeAssists(plugin, context,
@@ skipping 508 matching lines @@
     }
     if (refactoring is RenameRefactoring) {
       RenameRefactoring renameRefactoring = refactoring;
       RenameOptions renameOptions = params.options;
       renameRefactoring.newName = renameOptions.newName;
       return renameRefactoring.checkNewName();
     }
     return new RefactoringStatus();
   }
 }