Move scanner out of generated and clean up imports

pkg/analyzer/test/generated/incremental_scanner_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 analyzer.test.generated.incremental_scanner_test;
 
+import 'package:analyzer/dart/ast/token.dart';
+import 'package:analyzer/src/dart/scanner/reader.dart';
+import 'package:analyzer/src/dart/scanner/scanner.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/incremental_scanner.dart';
-import 'package:analyzer/src/generated/scanner.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:unittest/unittest.dart';
 
 import '../reflective_tests.dart';
 import '../utils.dart';
 import 'test_support.dart';
 
 main() {
   initializeTestEnvironment();
   runReflectiveTests(IncrementalScannerTest);
@@ skipping 516 matching lines @@
       incrementalToken = incrementalToken.next;
       modifiedTokens = modifiedTokens.next;
     }
     expect(incrementalToken.type, same(TokenType.EOF),
         reason: "Too many tokens");
     expect(modifiedTokens.type, same(TokenType.EOF),
         reason: "Not enough tokens");
     // TODO(brianwilkerson) Verify that the errors are correct?
   }
 }