Get memento objects from tasks, remember in cache and pass back to tasks.

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

Index: pkg/analyzer/lib/src/task/model.dart
diff --git a/pkg/analyzer/lib/src/task/model.dart b/pkg/analyzer/lib/src/task/model.dart
index 66ffb9ea93c350710d1c0640e52bfd3e52710d44..70a6d51ede746707b9a15a93646018be19773eac 100644
--- a/pkg/analyzer/lib/src/task/model.dart
+++ b/pkg/analyzer/lib/src/task/model.dart
@@ -121,9 +121,10 @@ class TaskDescriptorImpl implements TaskDescriptor {
 
   @override
   AnalysisTask createTask(AnalysisContext context, AnalysisTarget target,
-      Map<String, dynamic> inputs) {
+      Map<String, dynamic> inputs, dynamic inputMemento) {
     AnalysisTask task = buildTask(context, target);
     task.inputs = inputs;
+    task.inputMemento = inputMemento;
     return task;
   }