Use MODIFICATION_TIME in ScanDartTask and ParseHtmlTask.

pkg/analyzer/lib/src/task/html.dart

Index: pkg/analyzer/lib/src/task/html.dart
diff --git a/pkg/analyzer/lib/src/task/html.dart b/pkg/analyzer/lib/src/task/html.dart
index 257567764be06baa4dda3b18db1fcaf76b96226e..93e00edd8e905d4786983f91f8a575ff3e4004a1 100644
--- a/pkg/analyzer/lib/src/task/html.dart
+++ b/pkg/analyzer/lib/src/task/html.dart
@@ -269,6 +269,11 @@ class ParseHtmlTask extends SourceBasedAnalysisTask {
   static const String CONTENT_INPUT_NAME = 'CONTENT_INPUT_NAME';
 
   /**
+   * The name of the input whose value is the modification time of the file.
+   */
+  static const String MODIFICATION_TIME_INPUT = 'MODIFICATION_TIME_INPUT';
+
+  /**
    * The task descriptor describing this kind of task.
    */
   static final TaskDescriptor DESCRIPTOR = new TaskDescriptor(
@@ -292,7 +297,8 @@ class ParseHtmlTask extends SourceBasedAnalysisTask {
   void internalPerform() {
     String content = getRequiredInput(CONTENT_INPUT_NAME);
 
-    if (context.getModificationStamp(target.source) < 0) {
+    int modificationTime = getRequiredInput(MODIFICATION_TIME_INPUT);
+    if (modificationTime < 0) {
       String message = 'Content could not be read';
       if (context is InternalAnalysisContext) {
         CacheEntry entry =
@@ -343,7 +349,10 @@ class ParseHtmlTask extends SourceBasedAnalysisTask {
    * [source].
    */
   static Map<String, TaskInput> buildInputs(AnalysisTarget source) {
-    return <String, TaskInput>{CONTENT_INPUT_NAME: CONTENT.of(source)};
+    return <String, TaskInput>{
+      CONTENT_INPUT_NAME: CONTENT.of(source),
+      MODIFICATION_TIME_INPUT: MODIFICATION_TIME.of(source)
+    };
   }
 
   /**