Use MODIFICATION_TIME in ScanDartTask and ParseHtmlTask.

pkg/analyzer/test/src/task/html_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 analyzer.test.src.task.html_test;
 
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/task/html.dart';
 import 'package:analyzer/task/general.dart';
 import 'package:analyzer/task/html.dart';
@@ skipping 247 matching lines @@
     expect(outputs[HTML_ERRORS], isEmpty);
   }
 }
 
 @reflectiveTest
 class ParseHtmlTaskTest extends AbstractContextTest {
   test_buildInputs() {
     Source source = newSource('/test.html');
     Map<String, TaskInput> inputs = ParseHtmlTask.buildInputs(source);
     expect(inputs, isNotNull);
-    expect(inputs.keys, unorderedEquals([ParseHtmlTask.CONTENT_INPUT_NAME]));
+    expect(
+        inputs.keys,
+        unorderedEquals([
+          ParseHtmlTask.CONTENT_INPUT_NAME,
+          ParseHtmlTask.MODIFICATION_TIME_INPUT
+        ]));
   }
 
   test_constructor() {
     Source source = newSource('/test.html');
     ParseHtmlTask task = new ParseHtmlTask(context, source);
     expect(task, isNotNull);
     expect(task.context, context);
     expect(task.target, source);
   }
 
@@ skipping 87 matching lines @@
       expect(bodyElement.localName, 'body');
       // actual nodes
       expect(bodyElement.nodes, hasLength(4));
       expect((bodyElement.nodes[0] as Element).localName, 'div');
       expect((bodyElement.nodes[2] as Element).localName, 'span');
     }
     // it's OK to don't have DOCTYPE
     expect(outputs[HTML_DOCUMENT_ERRORS], isEmpty);
   }
 }