Remove memento.

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

Index: pkg/analyzer/lib/src/task/driver.dart
diff --git a/pkg/analyzer/lib/src/task/driver.dart b/pkg/analyzer/lib/src/task/driver.dart
index af608ad5616de98351ecfb541cb611da085bb100..4abd9b3fe8ab84c99cc850dfcea192b8a10d861f 100644
--- a/pkg/analyzer/lib/src/task/driver.dart
+++ b/pkg/analyzer/lib/src/task/driver.dart
@@ -125,9 +125,7 @@ class AnalysisDriver {
     }
     try {
       TaskDescriptor taskDescriptor = taskManager.findTask(target, result);
-      Object memento = entry.getMemento(result);
-      WorkItem workItem =
-          new WorkItem(context, target, taskDescriptor, memento);
+      WorkItem workItem = new WorkItem(context, target, taskDescriptor);
       return new WorkOrder(taskManager, workItem);
     } catch (exception, stackTrace) {
       throw new AnalysisException(
@@ -218,7 +216,7 @@ class AnalysisDriver {
       for (ResultDescriptor result in task.descriptor.results) {
         // TODO(brianwilkerson) We could check here that a value was produced
         // and throw an exception if not (unless we want to allow null values).
-        entry.setValue(result, outputs[result], dependedOn, task.outputMemento);
+        entry.setValue(result, outputs[result], dependedOn);
       }
     } else {
       entry.setErrorState(task.caughtException, item.descriptor.results);
@@ -283,12 +281,6 @@ class WorkItem {
   final TaskDescriptor descriptor;
 
   /**
-   * The optional data that the task associated with [target] last time.
-   * This data may help to compute outputs more efficiently.
-   */
-  final Object inputMemento;
-
-  /**
    * An iterator used to iterate over the descriptors of the inputs to the task,
    * or `null` if all of the inputs have been collected and the task can be
    * created.
@@ -318,7 +310,7 @@ class WorkItem {
    * Initialize a newly created work item to compute the inputs for the task
    * described by the given descriptor.
    */
-  WorkItem(this.context, this.target, this.descriptor, this.inputMemento) {
+  WorkItem(this.context, this.target, this.descriptor) {
     AnalysisTarget actualTarget = identical(
             target, AnalysisContextTarget.request)
         ? new AnalysisContextTarget(context)
@@ -339,7 +331,7 @@ class WorkItem {
     if (builder != null) {
       throw new StateError("some inputs have not been computed");
     }
-    return descriptor.createTask(context, target, inputs, inputMemento);
+    return descriptor.createTask(context, target, inputs);
   }
 
   /**
@@ -384,8 +376,7 @@ class WorkItem {
         try {
           TaskDescriptor descriptor =
               taskManager.findTask(inputTarget, inputResult);
-          Object memento = inputEntry.getMemento(inputResult);
-          return new WorkItem(context, inputTarget, descriptor, memento);
+          return new WorkItem(context, inputTarget, descriptor);
         } on AnalysisException catch (exception, stackTrace) {
           this.exception = new CaughtException(exception, stackTrace);
           return null;