Add error condition INVALID_OVERLAY_CHANGE to analysis server.

pkg/analysis_server/test/domain_analysis_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.domain.analysis;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/constants.dart';
@@ skipping 244 matching lines @@
           // reread from disk.
           helper.sendContentChange(new RemoveContentOverlay());
           // There should be errors now.
           return helper.waitForOperationsFinished().then((_) {
             expect(helper.getTestErrors(), hasLength(1));
           });
         });
       });
     });
   });
+
+  group('out of range', () {
+    Future outOfRangeTest(SourceEdit edit) {
+      AnalysisTestHelper helper = new AnalysisTestHelper();
+      helper.createSingleFileProject('library A;');
+      return helper.waitForOperationsFinished().then((_) {
+        helper.sendContentChange(new AddContentOverlay('library B;'));
+        return helper.waitForOperationsFinished().then((_) {
+          ChangeContentOverlay contentChange = new ChangeContentOverlay([edit]);
+          Request request = new AnalysisUpdateContentParams({
+            helper.testFile: contentChange}).toRequest('0');
+          Response response = helper.handler.handleRequest(request);
+          expect(response, isResponseFailure('0',
+              RequestErrorCode.INVALID_OVERLAY_CHANGE));
+        });
+      });
+    }
+
+    test('negative length', () {
+      return outOfRangeTest(new SourceEdit(3, -1, 'foo'));
+    });
+
+    test('negative offset', () {
+      return outOfRangeTest(new SourceEdit(-1, 3, 'foo'));
+    });
+
+    test('beyond end', () {
+      return outOfRangeTest(new SourceEdit(6, 6, 'foo'));
+    });
+  });
 }
 
 
 void test_setSubscriptions() {
   test('before analysis', () {
     AnalysisTestHelper helper = new AnalysisTestHelper();
     // subscribe
     helper.addAnalysisSubscriptionHighlights(helper.testFile);
     // create project
     helper.createSingleFileProject('int V = 42;');
@@ skipping 332 matching lines @@
     return waitForServerOperationsPerformed(server);
   }
 
   static String _getCodeString(code) {
     if (code is List<String>) {
       code = code.join('\n');
     }
     return code as String;
   }
 }