Fix "reanalyze sources" when there are unsaved files.

pkg/analyzer/test/generated/engine_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.
 
 // This code was auto-generated, is not intended to be edited, and is subject to
 // significant change. Please see the README file for more information.
 
 library engine.engine_test;
 
 import 'dart:async';
@@ skipping 6124 matching lines @@
       Source librarySource) {
     fail("Unexpected invocation of getResolvedCompilationUnit");
     return null;
   }
   @override
   ht.HtmlUnit getResolvedHtmlUnit(Source htmlSource) {
     fail("Unexpected invocation of getResolvedHtmlUnit");
     return null;
   }
   @override
+  bool handleContentsChanged(Source source, String originalContents,
+      String newContents, bool notify) {
+    fail("Unexpected invocation of handleContentsChanged");
+    return false;
+  }
+  @override
   bool isClientLibrary(Source librarySource) {
     fail("Unexpected invocation of isClientLibrary");
     return false;
   }
   @override
   bool isServerLibrary(Source librarySource) {
     fail("Unexpected invocation of isServerLibrary");
     return false;
   }
   @override
@@ skipping 38 matching lines @@
   }
   @override
   void setChangedContents(Source source, String contents, int offset,
       int oldLength, int newLength) {
     fail("Unexpected invocation of setChangedContents");
   }
   @override
   void setContents(Source source, String contents) {
     fail("Unexpected invocation of setContents");
   }
-
   @override
   void visitCacheItems(void callback(Source source, SourceEntry dartEntry,
       DataDescriptor rowDesc, CacheState state)) {
     fail("Unexpected invocation of visitCacheItems");
   }
 }
 
 
 class TestAnalysisContext_test_addSourceInfo extends TestAnalysisContext {
   bool invoked = false;
@@ skipping 863 matching lines @@
   bool contains(Source source) => source == libB;
 }
 
 
 class _UniversalCachePartitionTest_test_setMaxCacheSize implements
     CacheRetentionPolicy {
   @override
   RetentionPriority getAstPriority(Source source, SourceEntry sourceEntry) =>
       RetentionPriority.LOW;
 }